Overview Stimulated Brillouin Scattering
The SBS system is based on the measurement of the Brillouin Scattering characteristics. Brillouin scattering is a natural scattering process associated to the propagation of light in a medium like an optical fibre. Due to the interaction of light with the propagation medium different scattering components are generated: Rayleigh, Brillouin and Raman component (see Figure). The Brillouin interaction results in the generation of scattered light (Brillouin component) which shows a frequency shift compared to the light causing the interaction. This shift can be attributed to the presence of inhomogeneities associated to acoustic waves in the silica (acoustic phonons)
Figure: Scattering components in optical fibre
A system based on the analysis of the Brillouin scattered light in optical fibres is naturally devoted to perform strain and temperature measurement. This can be achieved since the Brillouin shift depends on the acoustic velocity of the medium, which is temperature and strain dependent.