Research On Key Technology Distributed Optical Fiber Temperature Sensor Based On Brillouin Seattering

The distributed optical fiber sensing technology based on the principle of Brillouin scattering is a new and cutting-edge optical fiber sensing technology, which has many advantages, such as long sensing distance, high spatial resolution and high accuracy, and it can measure both temperature and strain signal at the same time. Because of these advantages, this technology has become a hot topic in the field of optical fiber sensing.This paper introduces the background knowledge of Brillouin scattering in fiber, and the optical fiber sensing technology based on Brillouin scattering, then focused on distributed optical fiber temperature sensor key technologies research based on Brillouin scattering, including the following:We first analyze the characteristics of spontaneous Brillouin scattering and Brillouin scattering spectrum, then research theoretically on the relationship between the Brillouin frequency shift and the light intensity and sensing performance parameters such as temperature and strain.Then we introduce principles and characteristics of several different optical fiber sensors based on Brillouin scattering, including BOTDR, BTODA, BOFDA, and we especially discuss the optical fiber sensing system based on BOTDR, analyzing the principles and development of improving its performance, such as measuring range, spatial resolution and cross sensitivity in detail.Considering the simple structure and low cost of BOTDR system based on direct detecting, we propose a optical filter based on VIPA, which can be used for optical fiber sensing system based on BOTDR, first we analyze the characteristics of the VIPA filter, then we simulate the VIPA filter on computer, we also analyze the influence of the thickness and the angle of incidence on VIPA filter.Finally, we discuss the design of photodetector for optical fiber sensing in detail, including the basic theory of photodetector, design methods, and some measures to improve the sensitivity. We also analyze verify the relations between the Brillouin frequency shift and the temperature based on a sensing experiment. And we propose an optical fiber temperature sensing system based on BOTDR and VIPA filter, after introducing the characteristics of several key parts of the system, we give the experiment results.