Optical pulse coding in hybrid distributed sensing based on Raman and Brillouin scattering employing Fabry-Perot lasers.

We demonstrate simultaneous strain and temperature sensing based on hybrid Raman and Brillouin scattering with enhanced performance thanks to the combined use of standard Fabry-Perot lasers in conjunction with optical pulse coding techniques. The combination of both techniques allows for an improvement of ~8.7 dB in temperature resolution and ~3 dB in strain resolution, with respect to standard distributed feedback lasers, as confirmed by experiments, resulting in a final temperature / strain resolution of ~0.27K / ~30microepsilon over 25-km sensing fiber range, avoiding the use of optical amplification and wavelength averaging techniques.