The use of BOTDR to evaluate the thermal effects on fiber residual strain of optical fiber cables

摘要

The residual axial strain induced in the cabled fiber is a vital factor to evaluate the reliability of optical fiber cables. However, little is known about the thermal effect on the fiber residual strain, especially on the particular short section of the fiber. In order to precisely determine the thermal effects on fiber residual strain of optical cables, a measurement method based on Brillouin Optical Time-Domain Reflectometry (BOTDR) system is proposed. Thermal characteristics of fiber residual strain of optical fiber cables are investigated theoretically and experimentally. Measurements of the residual strain in particular short section of fiber are made with the distributed fiber sensing system based on BOTDR. Experimental results for a double-coated fiber in loose structure cable are in good agreement with those predicted from the theory. It has been found that the fiber residual strain increases linearly with the decrease of the temperature in the range from 50°C to -50°C.