Strain distribution measurement in optical cables using the multi-pointed fiber bragg gratings

摘要

Strain distribution along an optical fiber inside cables were optically measured by placing fiber Bragg gratings (EBG) with different reflecting wavelengths on the fiber. As a method for controlling the reflecting wavelength of each grating, various tension was applied to the fiber during UV exposure. We controlled the Bragg wavelength for 1 7nm (approx. 1.4% tension) with a single mask. Gratings were fabricated at regular intervals on a fiber for a slot type optical-fiber cable. The strain distribution induced by bending the cable was observed. Distribution measurements in a spatial resolution of 50mm, strain measurement precision of 0.002% was possible. We confirmed a strain distribution responding in accordance to the structure of the fiber locus inside slot type cables. The sensing fiber with multi-pointed FBGs has the same mechanical strength as normal fibers by UV exposed over the coating. Sensing fibers can be used in the cabling process and also in traction and installation.