Fiber sphere-embedded long-period fiber grating for curvature measurement with high sensitivity

摘要

A fiber sphere-embedded long-period fiber grating (LPFG) sensor has been proposed and fabricated for curvature measurement with high sensitivity. Compared with the normal LPFG, the embedded fiber sphere excites cladding modes and two dips of the output spectrum have been observed. The curvature measurement can be realized by monitoring the shift of the two dips. Experimental results show that the highest curvature sensitivity is up to -104.642 nmm~(-1) with the curvature ranging from 0 to 0.71 m~(-1). The temperature response of the sensor has also been studied and a quadratic linear relationship between the dip shift and the temperature has been observed. The highest temperature sensitivity is 0.36 nm/℃ with the temperature range between 20℃ and 90℃.