We propose and experimentally demonstrate the possibility to use a pump signal based on bipolar pulse sequences using single-sideband suppressed-carrier (SSB-SC) modulation in Brillouin optical time-domain analysis (BOTDA) sensors. The SSB-SC modulated pump makes a sequential use of the Brillouin gain and loss spectra, increasing the intensity contrast of the measurements. The method is demonstrated using bipolar Golay codes along a 50 km sensing fiber and 2 m spatial resolution. Results indicate that the use of bipolar sequences provides a higher SNR enhancement and stronger robustness to pump depletion in comparison to BOTDA systems employing conventional unipolar sequences.
Jürgen Brugger, Giovanni Boero, Philippe Marmillod, Alessandro Valentino Matheoud, Mario Andres Chavarria Varon
Drazen Dujic, Stefan Milovanovic