Research on the System of Pulse Synthesis Pre-pump Rayleigh BOTDA technology

Abstract

The conventional Rayleigh scattering Brillouin Optical Time Domain Analysis (Rayleigh BOTDA) system adopted the leakage light ahead of the pump pulse to generate Rayleigh back-scattering light. Stimulated Brillouin scattering (SBS) interacts between an optical pulse and a Rayleigh back-scattering light, then the temperature and strain information of the optical fiber are perceived by measuring the Rayleigh scattering light. However, the width of pulse is inversely proportional to the accuracy of spectrum detection, which means the narrower the pulse, the wider the Brillouin spectrum. But the spatial resolution is strictly related to the duration of the optical pulse, when the pulse width is less than the phonon lifetime, the Brillouin spectrum width is much larger than the Brillouin natural gain spectrum width. The spectrum detection accuracy of the system can be effectively improved by adding a pre-pump ahead of the pump pulse to stimulate the acoustic wave field in the Rayleigh BOTDA system. In this paper, we present a new method of synthesizing step pulse. Through the OpiSystem software simulation and Matlab software simulation, the influence of the pre-pump width and power on the performance of the system is analyzed and the feasibility of this method is confirmed by preliminary experiment.