Distributed fiber sensor based on modulated pulse base reflection and Brillouin gain spectrum analysis

In recent years, several distributed sensor systems based on stimulated Brillouin scattering in optical fibers have been proposed [ J. Intell. Mater. Syst. Struct. 10, 340 (1999); Proc. SPIE 5855, 555 (2005) ].We propose a simpler scheme based on fiber-end reflection and Brillouin gain spectrum analysis. In this setup, only one optical source is necessary to provide both the pump and the probe wave; the latter is provided by the modulated pulse base. First, the physical mechanisms for two different Brillouin scattering processes in our sensor system are analyzed and an approximate theory model is proposed. In addition, it is demonstrated that the simple system configuration allows simultaneous acquisition of the time-domain and the frequency-domain information. It is experimentally demonstrated that this configuration is effective for strain measurements and could as well be applied to temperature monitoring.