The interaction between light and sound in optical fibers is a phenomenon that researchers have been investigated for many decades. Among all the opto-acoustic effects that occurs in optical fibers, forward-stimulated Brillouin scattering (FSBS) has become of great interest as sensing mechanism due to the dependence of the excited acoustic resonances on both internal parameters [1] , [2] and surroundings [3] of the optical fiber. The vibrational modes behind FSBS are transverse acoustic resonances, in particular, the radial modes R 0m and the torsional-radial modes TR 2m . Most of the experiments reported based on FSBS exploit the properties of either the radial or the torsional-radial modes. In this work, we show that combining the characteristics of both types of resonances the possibilities of FSBS for fiber sensing can be extended further. In particular, we report the measurement of the Poisson ratio of the optical fiber with high accuracy, as well as its temperature dependence.
