Author Affiliations
Department of Electronics and Communication Engineering, North China Electric Power University, Baoding, Hebei 071003, Chinashow less
Fig. 1. Schematic of BOTDA system
Fig. 2. General schematic of BOTDA assisted by fiber Raman amplifier[8]
Fig. 3. Schematic of distributed fiber sensing based on random laser[15]
Fig. 4. SNR degradation of signal detected by BOTDA as a function of RIN level of Raman pump light[16]
Fig. 5. Experimental setup for the Simplex coded-BOTDA sensor[18]
Fig. 6. Experimental validation of the Simplex coded-BOTDA assisted by EDFA[23]. (a) Measured profile of BGS; (b) measured profile of BFS versus distance
Fig. 7. Schematic of conventional sequences and hybrid sequences[34]
Fig. 8. Comparison in BFS distribution between measurements with Walsh code and the conventional PSP-BOTDA system[36]
Fig. 9. Schematic of Simplex coding pre-pumped pulse[40]. (a) Conventional pump pulse and pre-pumped pulse; (b) conventional pump pulse and pre-pumped pulse of 3 bit Simplex coding
Fig. 10. Brillouin interaction and frequency modulation in the dual-probe BOTDA[46]. (a) Brillouin interaction of the conventional dual-probe BOTDA; (b) Brillouin interaction of the dual-probe BOTDA with the pump shifted in frequency; (c) combination of BGS and BLS for the dual-probe BOTDA with the pump shifted in frequency; (d) frequency modulation in the dual-probe BOTDA
Fig. 11. Experimental setup of BOTDA based on coherent detection[48]
Fig. 12. Experimental setup of BOTDA with balanced detection[49]
Fig. 13. Schematic of the frequency modulation and time multiplexing of multi-frequency pump light[51]
Fig. 14. Experimental setup for BOTDA based on multi-frequency time-shifted pump pulses[51]