Long-distance BOTDR system based on multiple-EDFA online amplification

A long-distance BOTDR system based on multiple-EDFA (short for erbium-doped optical fiber amplifier) online amplification comprises a narrow-linewidth laser, an electrooptical modulator, an optical circulator, a sensing fiber, the erbium-doped optical fiber amplifiers, an optical filter, a photoelectric detector and a signal processing circuit, wherein the electrooptical modulator is connected between the narrow-linewidth laser and the optical circulator, the optical filter is connected between the photoelectric detector and the optical circulator, the photoelectric detector is further connected with the signal processing circuit, one end of the sensing fiber is connected with the optical circulator, the sensing fiber is evenly divided into N sections, the erbium-doped optical fiber amplifiers are connected between every two adjacent sections of sensing fiber, N is a positive integer, and the gain coefficients of the erbium-doped optical fiber amplifiers are identical and are loss of light in each section of fiber. The long-distance BOTDR system based on multiple-EDFA online amplification has the advantages of being capable of compensating signal attenuation and increasing distributed optical fiber sensing distance.