Cyclic pulse coding for hybrid fast BOTDA/Raman sensor

We propose and experimentally demonstrate a fully hybrid distributed sensing scheme that uses a single narrow-band laser to perform fast measurement of the BFS using BOTDA and simultaneous temperature measurement based on spontaneous Raman scattering over 10 km of single mode fiber. The use of cyclic pulse coding effectively reduces the pump peak power levels required for accurate Raman-based distributed temperature measurement, enhancing at the same time the speed of the BFS measurement in the BOTDA technique.