Effects of Bending Radius and Fiber-Crack Angle on Polymer Optical Fiber Loss for Potential Application in Pavement Crack Monitoring

This paper investigates the potential of polymer optical fiber (POF) in pavement crack monitoring. Firstly, the critical radius of macrobending and microbending of POF was analyzed theoretically. Then, the relationship between the bending loss and the bending radius was established and verified by experiments, and a reasonable bending radius was recommended. Subsequently, the POF was fixed on a simulated pavement with various fiber-crack angles, and the effect of fiber-crack angles on light loss was analyzed. The results showed that the optical loss decreased exponentially with the increase of the bending radius when the bending radius was less than 8 mm, but it changed slowly when the bending radius was more than 8 mm. The output optical power value was related to the initial fiber-crack angle and the bending radius. Under the same bending radius, the optical loss became greater if the initial fiber-crack angle was smaller.