Use of Fabry-Pérot lasers for simultaneous distributed strain and temperature sensing based on hybrid Raman and Brillouin scattering

In this paper we propose the use of multi-longitudinal mode lasers, such as Fabry-Pérot (FP) lasers, for simultaneous distributed strain and temperature sensing based on hybrid Brillouin and Raman scattering. Fabry-Pérot lasers allow for high-power Raman intensity measurement and the simultaneous detection of the Brillouin frequency shift parameter for all FP longitudinal modes, by using a self-heterodyne detection scheme based on a multi-wavelength optical local oscillator. Experiments point out significant improvement in hybrid sensor performance, also suggesting further potential benefits when combining the use of FP lasers with optical coding techniques and/or optical amplification.