Brillouin Characterization of Fiber Strain in Bent Slot-Type Optical-Fiber Cables

A technique is proposed based on Brillouin gain spectroscopy to evaluate tensile and compressive strain variations in optical fibers. This technique is applied to characterize fiber strain in bent slot-type optical-fiber cables. Fiber ribbons containing 4 optical fibers each are stranded through the cable. When the cable is bent, two types of strain are created in the fiber. It was found from experimental results that the first strain, which was induced by the elongation and compression of the fiber ribbon along its length, was drastically reduced, while the second strain, which was created by bending the fiber ribbon in its plane surface, remained.