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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 principle of mode interference optical fiber sensor and improve the performance of strain sensor accordingly, a PMF based mode interference strain sensor is proposed. Between two single-mode fibers (SMFs), a lumbar 30mm long PMF was enlarged and fused to form an all-fiber mode interference sensor. Strain changes will cause changes in the phase difference between the core and cladding modes of the fiber, resulting in changes in the interference spectrum. In the strain range of 0 ~ 3 605με, through a spectrometer (OSA) detection of broadband light source through the optical fiber sensor after the transmission spectrum. The least square method was used to fit the intensity and strain linearly. It was found that there was a high linear relationship between the decreasing trend of light intensity and the change of strain, and the sensitivity of strain was 0.004dB / με. The corresponding resolution Is 2.5με. The sensor of this paper is simple to manufacture, low cost and stable structure, and has high resolution, so it is suitable for the actual measurement.