Inelastic scatterings turn out to occupy an essential place in sensing applications, since they simply require a plain optical fibre as sensing element, with no special preparation. They give rise to energy and momentum transfers with the fibre material and make thus possible to access to material properties other than the simple optical linear response. In addition, inelastic scatterings can exist in a stimulated flavour that gives rise to dynamic couplings between all the waves involved in the interaction. This way efficient energy transfers between optical waves can be realized via the intercession of material vibrations to eventually generate optical amplification.