Stimulated Brillouin scattering in multi-mode optical fibers: Toward plastic-fiber-based BOTDA

Based on pump-probe technique (PPT), we observed stimulated Brillouin scattering (SBS) in a 100-m-long silica graded-index multimode optical fiber with the same core diameter as that of a perfluorinated graded-index polymer optical fiber (PFGI-POF) (= 50 μm). The SBS threshold was measured to be -50 mW, which was much lower than 5.08 W, the SBS threshold obtained for the same fiber without PPT. This result indicates that PPT is useful even under multimode conditions and that the difficulty in observing SBS in PFGI-POFs consists not in their physical problems but in their material problems (high propagation loss, etc.).