The Research Of Distributed Optical Fiber Sensing Based On BOTDA

In recent years, most of the research in the area of distributed fiber optic sensing focused onincreasing the overall sensing length and improving spatial resolution. For applications like civilstructural monitoring and aerospace vehicle sensing, current centimeter resolutions and kilometerranges yield much useful information but lack the acquisition speed to produce dynamic strain.The time it takes to make a typical measurement using current Brillouin technology is severalminutes and hence the results are instantaneous but instantly available, rendering them not usefulfor dynamic measurements.This thesis introduces the characteristics of the optical fiber sensor and some methods thatare widely used in practical application.Then the principle of Brillouin scattering is argued.Thisthesis also researchs some key performance indicators of sening system such as Minimumdetectable parameter dynamic range and space resolution. Some key components of Brllouinsensing system was introduced in this thesis such as laser EOM and lock-in amplifier. Anapplication of BOTDA has been chosen as the example for research.The mathematicalformulation and simulation model of Brillouin interaction was developed in Matlab. The signalof summation of sinusoids with random phase was simulated. Also, the amplitude modulationwas chosen in the system. It was found to have better effect than phase modulation to obtainBrillouin interaction. At last an algorithm was proposed to use for post processing.