Research On Detection Of Seismic Wave Of Eccentric Core Fiber

In recent years,optical fiber sensor which is applied to the detection of earthquake has developed to be a new kind of seismic wave detection technology.Moreover, optical fiber detector, compared with traditional geophone, has good resistance to electromagnetic interference, insulation and networking capability, etc, while it could have a very good development potential in earthquake monitoring, and oil-gas exploration.In addition, eccentric core optical fiber has more unique advantages in the optical fiber sensing, because it is more sensitive to the outside environment change than ordinary optical fiber. In this paper, based on eccentric core optical fiber,it combines with the optical fiber sensing technology, seismic wave propagation theory and vibration testing technology to design a kind of seismic wave detection system.Firstly, it has a commentary on the geophone technology, especially for thetraditional electrodynamic geophone detector and the detection principle of MEMSdetection and have done detailed narration. It analyzes the propagation mechanismand characteristics of longitudinal wave, shear wave and the Rayleigh wave in theideal medium.Secondly, it gives out the theoretical model of the eccentric core optical fiberand has a analysis of evanescent field in eccentric core optical fiber. Throughaconformal mapping transform, it can obtain the characteristic equation andpropagation constant of eccentric optical fiber. And using Rsoft software foreccentric core optical fiber mode field and power are simulated.Finally, according to the principle of a Michelson interferometer, it designs a three-component geophone based on eccentric core optical fiber. Through analyzing the natural frequency of the detector and phase acceleration sensitivity, a three-component fiber-optic seismic wave detection system is designed, and the theoretical structure are verified through experiments.