Double-pulse Brillouin distributed optical fiber sensors: analytical model and experimental validation

An analytical model is presented to describe the behavior of the acoustic wave, probe signal and Brillouin gain in double-pulse Brillouin optical time-domain analysis (DP-BOTDA) sensors. The proposed model is a tool that provides a full physical insight into the Brillouin interaction occurring in this double-pulse configuration, and allows the optimization and complete analysis of the system. The proposed solution is experimentally validated in a long-range system, which is optimized to demonstrate experimentally, for the first time, the capability of DP-BOTDA to achieve a 11 km sensing distance with 20 cm spatial resolution and a frequency resolution of 0.5 MHz.