Research on long-distance BOTDR sensing system based on Raman amplification
Brillouin optical time domain reflectometry (BOTDR ) system realizes fully distributed temperature and strain sensing along the sensing fiber.However,due to the fiber loss,Brillouin signal light is often submerged in noise after long-distance transmission,and the signal-to-noise ratio is extremely low.Through the gain effect of Raman pump on the whole Brillouin signal of optical fiber,this paper investigates the difference of system measurement distance before and after Raman amplification. Moreover,the corresponding amplification curves under different pump powers are compared. Our experiments show the measurement distance of the BOTDR sensing system based on Raman amplification rises to the order of 100 km,and the temperature at the end of the fiber at 103 km is successfully measured at a spatial resolution of 50 m,and the measurement accuracy of 2.19 ℃ is obtained.
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