Design and implementation of spontaneous Brillouin scattering based double-trace distributed optical fiber sensor

On the basis of linear dependence of Brillouin frequency shift in fiber on both strain and temperature,this paper proposes a distributed fiber sensing system based on spontaneous Brillouin back-scattering light.By the differences of Brillouin shifts from different kinds of optical fibers,this system can be used to distinguish the sensing area,and to obtain the temperature and strain information of different lines at the same time,so that the detecting time is shortened and work efficiency is improved.Proposed system realizes synchronous detection for two optical fiber lines,and obtains the 4 m resolution when a 6 km fiber is used as sensing media.Obtained experimental results show that the system can get the variety of the spontaneous Brillouin back-scattering light caused by a 40 ns pulse in the two sensing lines.