Pump depletion reduction technique for extended-range distributed Brillouin fiber sensors

We present a numerical and experimental analysis of a technical solution, capable of alleviating the problem of pump depletion in a long-range Brillouin distributed fiber sensor. This solution takes advantage of the presence of two sidebands in the probe wave to generate a dual gain-loss Brillouin interaction, giving rise to reduced pump depletion. Experimental results, carried out by using both a Brillouin optical frequency-domain analysis (BOFDA) configuration and a Brillouin optical time-domain analysis (BOTDA) configuration, permitted to evaluate the advantages and limitations of the gain-loss technique. An extensive experimental and numerical analysis has been carried out, in order to understand the differences on the effectiveness of the technique, between BOTDA and BOFDA set-ups.