一种改进的三波长EFPI小信号解调方法  

A Modified Three-wavelength Demodulation Method for Small Signals of EFPI

作　　者：杨芮牧 董小鹏 YANG Ruimu;DONG Xiaopeng(Institute of the Lightwave Technology,School of Electronic Science and Engineering,Xiamen University,Xiamen 361000,China)

机构地区：[1]厦门大学电子科学与技术学院光波技术研究所,厦门361000

出　　处：《光子学报》2023年第8期52-63,共12页Acta Photonica Sinica

基　　金：国家自然科学基金(No.61775186);厦门市海洋发展局(No.16CZB025SF03);厦门市光通讯器件测试重点实验室项目。

摘　　要：针对非本征法布里-珀罗干涉型(EFPI)传感器采用对称三波长解调法检测小信号时可能存在的波形变差问题,提出一种针对小信号的改进的对称三波长解调方法。利用三角函数的小信号近似,得到简化的公式计算求出三路信号的相位差,解决EFPI干涉信号的衰落问题。仿真与实验结果表明,该方法在针对小信号解调方面比现有三波长法具有更高的算法稳定性与更小的误差,同时在低信噪比的场景下对波形具有更好的恢复效果。实验上分别用本文方法和现有方法对相同声波信号进行解调,本文方法解调的信噪比较现有方法高12 dB以上。Fiber optic Extrinsic Fabry-Perot Interferometers (EFPI) are frequently utilized in many acoustic sensing scenarios due to their simple structure,ease of fabrication,high sensitivity,high phase consistency,and strong resistance to electromagnetic interference.However,the cavity length of the EFPI sensor is susceptible to environmental variables such as temperature and air pressure,and the drifting of the orthogonal working point caused by the change of cavity length will lead to signal fading and distortion.Nevertheless,several demodulation methods are less practical or even ineffective when dealing with small signals:Dual-wavelength method for Mach-Zehnder interferometer is inconvenient to apply to the EFPI demodulation;the Ellipse-Fitting Algorithm's (EFA) Lissajous figure will degenerate into a straight line for small signals,and there are also the disadvantages of poor real-time performance and slow demodulation speed;the second-order Differentiate-and-Cross-Multiply (DCM) operation has wide applicability,but the Direct Current (DC) term must be accurately removed,for small signals,the removal of DC term is difficult;the Bessel method has the same difficulties as DCM,and it can only demodulate single-frequency signals;The method of using tunable laser feedback to control the orthogonal working point has the drawback of high cost,and lasers with wavelength scanning function have high requirements for hardware reliability;Phase Generated Carrier (PGC) technology requires a complex carrier modulation system with a limited frequency response range,and the system is complex and large when PGC uses piezoelectric transducer to generate phase carriers.In contrast,intensity demodulation has the advantages of a linear transfer function,simple signal processing,high sensitivity and is suitable for the detection of high-speed and small signal.JIANG Yi et al.proposed a Symmetrical Demodulation Method(SDM) suitable for unstable cavity length and unknown cavity length,which constructs two equal interference phase difference

关 键 词：非本征法布里-珀罗干涉仪 三波长解调 信号衰落 声波检测 小信号 

分 类 号：TN29[电子电信—物理电子学]