Research And Optimization Of Brillouin Optical Time Domain Analyzer Based On Microwave External Modulation

Distributed fiber sensor which takes optical fiber as sensing carrier, is characterized by long distance, high sensitivity and good space adaptability. It can be used for measuring the continuous sensing information in the space and time. This making distributed fiber sensor technology becomes a mainstream sensing technology with a good development prospect. However, the fiber sensor also have some disadvantages like low sensitivity and insufficient space resolution in security and protection, structure monitoring and aerospace and etc. Distributed fiber sensor with these disadvantages can’t meet some actual needs. Therefore, this paper showed some research on how to get the high spatial resolution and high measurement accuracy, and supply an resolution- a fiber sensor with single light source and optical circuits.Base on the basic theory of the back-scatter light in the fiber, therefore infer the process which kinds of back-scatter light come out, specially focus on the Brillouin back-scatter light. Along with the principle of Brillouin back-scatter light, this paper built up the signal theoretical model of Brillouin back-scatter light, and did some study in the effect factors in the Brillouin scatter light, and simulated the scatter light working with different temperatures and strain.According to Stimulated Brillouin Amplication and Microwave Electric-Optical Modulation Technology, this paper built up a new Brillouin Optical fiber Time Domain Analysis(BOTDA)system. The operating principle of BOTDA system was illustrated in detail, and the effect of key factors( spatial resolution and measurement accuracy, testing distance and etc.) was discussed. The core component and calculate the data of the components had been chosen.On the basis of theory model of BO TDA system, this paper made the system in the experiment lab, got the Brillouin signal and modulated pump. This paper chose the overlapping average algorithm to calculate the original resource. At last, this paper got the result of the BO TDA working data with temperatures and stain response. After the analysis, the spatial resolution of the system is 1m and measurement of the stain range can be 3710.56 με(389.46g); the working temperature can reaches 80 °C; the measurement accuracy at the stain and temperature is 20 με and 0.8 °C.