A reconstruction technique for stimulated Brillouin scattering fiber-optic sensors for simultaneous measurement of temperature and strain

A novel approach for simultaneous temperature and strain profiles reconstruction, based on Brillouin optical-fiber time-domain analysis (BOTDA) sensors, is proposed. In this approach, the unknown profiles are expanded in base harmonic functions, while evaluating their coefficients by means of a multidimensional minimization. In order to discriminate between strain and temperature effects on Brillouin frequency changes, a suitable deployment of the fiber acting as a sensor is supposed, so as half of its sensing length is subject to the influence of variations in both strain and temperature, whereas the other half is isolated from the effects of mechanical strain. Numerical simulations, even in presence of noise, have proved the capability of the proposed algorithm to compensate for some systematic errors suffered by classical approaches based on the direct reading of Brillouin power spectra.