Fig. 1. Diagram of DPP-BOTDA based on gain and loss

Fig. 2. Pulse sequence amplified by EDFA

Fig. 3. 32-bit Golay code. (a) Cross-correlation result; (b) decoding result

Fig. 4. Coding gain of the Simplex code as a function of code length

Fig. 5. Diagram of gain-loss DPP-BOTDA system

Fig. 6. Experimental results. (a) Amplification of EDFA for different code length sequences; (b) time-domain signal at the end of the fiber for different code length sequences

Fig. 7. Brillouin spectrum obtained with different probing pulses

Fig. 8. Experimental results. (a) Time-domain signal of the heated segment for utilizing 32-bit Simplex pulse sequences at different temperatures; (b) Brillouin spectrum varies with temperature