Research On The Temperature/strain Sensing Technology Based On BOTDA System

The Brillouin optical-fiber time domain analysis (BOTDA) technology based on stimulated Brillouin scattering (SBS) have been studied in this thesis. The dependences of Brillouin shift on temperature and strain are investigated theoretically. The expression of SBS power has been derived from SBS coupled equations and then simulated numerically. A microwave exo-modulation BOTDA sensing system with high spatial resolution and measurement accuracy for temperature and strain has been proposed and designed. The microwave modulation characteristic of electro-optical modulator (EOM) has been researched. A plan of double fiber has been proposed to improve signal-to-noise ratio (SNR) and reliability. The system performance such as SNR, measurement accuracy, linewidth and step have been analyzed and simulated. When the extinction ratio of EOM is finite, SBS effect is influenced by the leaked light, which can be used as an accurate signal processing methods. By simulating the Brillouin signal spectrum, measuring length which is less than theoretical spatial resolution and Brillouin frequency range have been obtained.