Distributed strain and temperature sensing over 50 km of SMF with 1 m spatial resolution employing BOTDA and optical pulse coding

In this paper we demonstrate a long-range distributed strain and temperature optical fiber sensor using Brillouin optical time-domain analysis in conjunction with optical pulse coding. Compared to standard BOTDA, pulse coding provides higher signal-to-noise ratio at the same pump peak power, overcoming the limitations induced by pump depletion and modulation instability, and allowing to achieve a record of 1 meter spatial resolution over 50 km of standard single mode fiber with temperature and strain resolution of 2.2 °C and 44 µepsilon respectively.