A Study on the Jacket Effect of Fiber Optic Sensor

摘要

With the rapid development of distributed fiber optic sensor, such as Brillouin Optical Time Domain Reflectometry (BOTDR), much more importance is attached to the performance of optical fiber. As a conductive and sensing element, optical fiber must be protected from damage and meanwhile be sensitive to strain and temperature. Therefore, tight-buffered optical fiber with a jacket is often used in a certain harsh environment instead of ordinary optical fiber. The jacket can protect optical fiber, on the other hand, exert effect on the optical fiber's sensitivity to temperature and strain. In this paper, two types of optical fiber, i.e. with jacket (Type-A) and without jacket (Type-B),were selected to study the jacket effect on strain measurement, and relative experiment schemes and results are present. It is found that the strain of Type-A, measured by BOTDR, changed with time under constant load stretching within 48 hours, while the Type-B kept constant. After that the load was removed to let the fiber relax. After several days, then again loaded and measured.Through three cycles, the strain measurements of the Type-A gradually increased, but the accretions become smaller and smaller. These experiment results indicate that the jacket has the creep deformation that effects the strain measurement.