Unambiguous Peak Identification of a Silicon Fabry-Perot Temperature Sensor Assisted With an In-Line Fiber Bragg Grating
Unambiguous Peak Identification of a Silicon Fabry-Perot Temperature Sensor Assisted With an In-Line Fiber Bragg Grating
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DOI：
10.1109/jlt.2019.2921920
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发表时间：
2019-09-01
影响因子：
4.7
通讯作者：
Han, Ming
中科院分区：
文献类型：
--
作者：
Liu, Zigeng;Liu, Guigen;Han, Ming
波长解调法因其高的测量分辨率而被广泛应用于基于法布里-珀罗干涉仪（FPI）的光纤传感器。然而，相位模糊往往限制测量范围小于一个自由频谱范围（FSR）的FPI。在这里，我们研究了一种简单而有效的方法，可以消除相位模糊的硅FPI温度传感器使用的光纤布拉格光栅（FBG）上制作的引入光纤接近硅FPI。传感器的反射光谱显示来自FPI的正弦条纹和来自FBG的单峰。假设FBG和硅FPI具有相似的温度，FBG峰值可以仅用作标识FPI条纹峰值的标记，即使当其偏移超过FSR时也没有模糊性。虽然FBG的温度分辨率低于硅FPI的温度分辨率，但硅FPI的测量范围可以在不牺牲测量分辨率的情况下大大提高。使用基于75 μ m厚硅FPI的温度传感器，我们演示了在-60至140摄氏度范围内的温度测量（对应于约5个FSR的光谱偏移），分辨率为0.0033摄氏度。具有明确峰值识别的测量范围预计将大于实验中证明的范围，并且仅受传感器系统的光谱带宽和用于传感器构造的材料的能力的限制。
Wavelength interrogation has been widely used for fiber-optic sensors based on Fabry-Perot interferometers (FPIs) because of its high measurement resolution. However, phase ambiguity often limits the measurement range to be less than one free-spectral range (FSR) of the FPI. Here, we investigate a simple but effective method that can eliminate the phase ambiguity of a silicon FPI temperature sensor using a fiber Bragg grating (FBG) fabricated on the lead-in fiber close to the silicon FPI. The reflection spectrum of the sensor shows sinusoidal fringes from the FPI and a single peak from the FBG. Assuming the FBG and the silicon FPI have similar temperatures, the FBG peak can be used merely as a marker to identify an FPI fringe peak without ambiguity even when it shifts by more than an FSR. Although the temperature resolution of the FBG is lower than that of the silicon FPI, the measurement range of the silicon FPI can be greatly improved without sacrificing the measurement resolution. Using a temperature sensor based on a 75-mu m-thick silicon FPI, we demonstrated temperature measurement over a range of -60 to 140 degrees C (corresponding to a spectral shift of about five FSRs) with a resolution of 0.0033 degrees C. The measurement range with unambiguous peak recognition is expected to be larger than demonstrated in the experiment and only limited by the spectral bandwidth of the sensor system and the capability of materials used for the sensor construction.