基于花生形和光纤布喇格光栅结构的温度不敏感光纤曲率传感器

Temperature-insensitive Curvature Sensor Based on a Peanut-shape Structure and a FBG

为了解决光纤传感器波长解调成本高以及交叉敏感的问题,提出一种温度不敏感光纤曲率传感器,该传感器是由花生形结构连接一个光纤布喇格光栅组成,对反射光采用强度解调.光进入花生形结构后激发出包层模式,通过光纤布喇格光栅反射后,反射的纤芯模再次在花生形结构产生不同阶次的包层模,然后和反射的纤芯模耦合,在反射光谱中除了光纤布喇格光栅的布喇格反射峰外,在短波长处出现若干个谐振峰,波长越小,包层模的阶次越高.实验结果表明曲率的变化范围为0.669 0~1.250 0m^(-1)时,测量到反射谐振峰平均光功率为2.260×10^(-7)~1.501×10^(-7) mW,灵敏度为-1.306×10^(-7) mW/m-1,在温度范围25℃~75℃内,反射包层模光功率基本保持不变.该传感器成本低且花生形结构制作简单、机械强度大.

Abstrac A temperature-independent curvature sensor was presented for solving the high cost of wavelength demodulation and cross sensitive problem. The sensor consists of a fiber Bragg grating spliced after a peanut-shaped fiber, and it is reflected light intensity demodulation. With the broadband light entering the peanut-shaped structure, the cladding mode is excited, being reflected by the FBG, the reflected core mode is excited by the peanut-shape structure again making several ranking cladding modes, which interference with the core mode. The reflected spectrums not only consist of the FBG peak but also consist of several resonant peaks, the shorter the wavelength is, the higher ranking of the cladding mode is. The experiment results show that the intensity of the reflected resonant peaks decreases from 2.260× 10^-7 mW to 1. 501× 10^-7 mW with the curvature increases from 0. 669 0 m^-1 to 1. 250 0 m^-1. The average curvature sensitivity is -- 1. 306 × 10^-7 nW/ m^-1. Temperature test on the structure shows that the power of the reflected cladding modes made little change with temperature increases from 25℃ to 75℃. The proposed curvature sensors is less expensive and the peanut-shaped structure has the feature of easy making and high mechanical strength etc.