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实现了一种基于光纤布拉格光栅(FBG)及其末端镀膜的高灵敏度Ni~(2+)浓度光纤传感器。壳聚糖和聚丙烯酸(PAA)通过自组装,以聚合物膜的形式直接聚合沉积在光纤末端。当Ni~(2+)因螯合作用而被膜吸附时,膜的折射率发生变化,从而使光纤末端的菲涅尔反射发生改变。通过测量菲涅尔反射光谱中信噪比(SNR)的变化,就可以得到Ni~(2+)的浓度。实验测得传感器的最大线性灵敏度可达35.52dB/mM。利用SNR解调的方法不仅可以消除光源功率波动对测量精度的影响,同时可以利用FBG谐振波长的漂移测量温度变化。本文实现的Ni~(2+)浓度光纤传感器,具有良好的灵敏度、成本低和结构简单等优点。
A high sensitivity Ni 2+ optical fiber sensor based on fiber Bragg grating (FBG) and its end coating is realized. Chitosan and polyacrylic acid (PAA) are directly polymerized and deposited on the fiber end by self-assembly in the form of polymer films. When Ni 2+ is absorbed by the membrane due to chelation, the refractive index of the film changes so that the Fresnel reflection at the end of the fiber changes. By measuring the change of signal-to-noise ratio (SNR) in the Fresnel reflection spectrum, the Ni2 + concentration can be obtained. The maximum linear sensitivity of the sensor measured experimentally can reach 35.52dB / mM. The method of SNR demodulation can not only eliminate the influence of the power fluctuation of the light source on the measurement accuracy, but also measure the temperature variation by the drift of the FBG resonant wavelength. The Ni2 + concentration fiber sensor realized in this paper has the advantages of good sensitivity, low cost and simple structure.