Research Of BOTDR System Based On The Single Frequency Power Of The Brillouin Spectrum

As a sensor unit and transmission medium,the distributed optical fiber sensing technology has many advantages,such as corrosion resistance,long life,all-round distribution and easy networking,and has been widely used in the sensing field.The Brillouin optical time-domain reflectometry(BOTDR)is a single-end measurement that can measure the temperature/strain distribution along the fiber at the same time,and can measure the break point of the fiber.So it is widely used in health monitoring of large-scale structures such as tunnels,highways,tall buildings,submarine optical cables.The BOTDR technology obtain the temperature/strain distribution along the fiber by detecting the spontaneous Brillouin scattering signal in the optical fiber and analyzing the spectral information of the spontaneous Brillouin backscattering according to the linearity between the Brillouin frequency shift and the temperature or the strain.However,Brillouin scattering spectrum is usually acquired by using frequency sweeping method due to the wide full width at half maximum of Brillouin scattering,and since the spontaneous Brillouin scattering signal is very weak,it is usually necessary to use the cumulative average method to improve signal-to-noise ratio.This leads to a serious deficiency in the BOTDR system:the measurement time is too long.Therefore,BOTDR systems are difficult to apply in areas where real-time requirements are high.Aiming at the deficiencies of the above BOTDR system,this paper analyzes the characteristics of Brillouin scattering spectrum,and proposes a measurement method based on Brillouin spectrum single-frequency power to overcome this deficiency,and A supporting automatic monitoring software is designed on the Lab VIEW platform.And temperature experiments were carried out.The results show that the method is feasible and the software meets the predetermined designing requirements.