对弯曲不敏感的长周期光纤光栅传感器

发现了用高频CO₂激光写入的长周期光纤光栅的谐振波长对弯曲灵敏度在圆周的不同方向上呈现周期性,且在两个特定的对称方向上对弯曲不敏感(即弯曲曲率达到1.1m^-1,谐振波长仅漂移-0.018nm).据此提出新型对弯曲不敏感的传感器和可调灵敏度弯曲传感器的设计方案,可望从根本上解决长周期光纤光栅在测量中存在的温度、应变或折射率与弯曲之间的交叉敏感问题.

BEND-INSENSITIVE LONG-PERIOD FIBER GRATING SENSORS

A novel bend insensitive long period fiber grating(LPFG) sensor written with high frequency CO 2 laser pulses is demonstrated in this paper.Experimental results show that the resonant wavelength shift of the LPFG is only -0.018nm even a curvature of 1.1m -1 applied to the LPFG.Quantitative measurements also show that the bend sensitivity against the resonant wavelength shift has a periodic distribution along circular directiom.Based on these results,this paper proposes two approaches for sensor design.One is to achieve bend insensitive measurement of temperature,strain or refractive index using the LPFG fabricated and the other one is to realize a bend sensor with adjustable sensitivity by selecting the rotation position of the LPFG.Such a bend insensitive sensor could solve the problem of cross sensitivity between bend and other measurands,which is an unsolved problem for LPFG sensors currently.