基于保偏光纤模式干涉的应变传感器研究

Strain sensor based on modal interference of polarization maintaining fiber

为了进一步了解模式干涉光纤传感器的原理,并相应提高应变传感器的性能,提出一种基于保偏光纤(PMF)的模式干涉应变传感器。在两根单模光纤(SMF)之间,腰椎放大熔接一根长30mm的PMF,构成全光纤模式干涉传感器。应变的变化将会引起光纤的纤芯模与包层模相位差的变化,从而导致干涉光谱的变化。在应变范围为0～3 605με,通过光谱仪(OSA)检测宽带光源经光纤传感器后的透射光谱。采用最小二乘法对光强强度和应变进行线性拟合,发现光强减小的趋势与应变的变化有很高的线性关系,并测得应变的灵敏度可达到0.004dB/με,对应的分辨率为2.5με。本文传感器制造简单、费用较低和结构稳固,并且具有很高的分辨率,因此适用于实际测量。

In order to further understand the modal interference principle of fiber optic sensors and improve the performance of the strain sensor,a novel fiber sensor based on modal interference of polarization maintaining fiber for strain measurement is proposed. A length of 30 mm polarization maintaining fiber （PMF） is spliced with waist enlarge between two conventional single-mode fibers （SMFs） to construct an all-fiber modal interferometer sensor. The phase difference between the cladding and core regions of the fiber changes with the external strain increases, and then the interference spectrum changes. The optical spectrum analyzer （OSA） is used to defect transmission spectrum of a gain-flattened erbiumdoped fiber with amplified spontaneous emission （ASE） through the sensor in the strain range from 0με to 3 605 με. The results show that the light intensity and the strain have highly linear relationship using the method of least squares linear fitting. The sensitivity can be 0. 004 dB/με, and the corresponding resolution is 2. 5 με. The presented sensor is with simple manufacturing, relatively low cost, solid structure and high resolution,so it is suitable for strain measurement in Dractice.