Opt Express. 2023 Apr 24;31(9):14119-14127. doi: 10.1364/OE.487946.
An FBG sensor interrogated by an optical carrier microwave interferometry (OCMI)-based three-arm Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. In our sensing scheme, the interferogram generated by interfering the three-arm-MZI middle arm with the sensing arm and the reference arm respectively is superimposed to produce a Vernier effect to increase the sensitivity of the system. The simultaneous interrogation of the sensing fiber Bragg grating (FBG) and the reference FBG by the OCMI-based three-arm-MZI provides an ideal solution to the cross-sensitivity problems (e.g. temperature vs. strain) associated with conventional sensors that produce the Vernier effect by cascading optical elements. Experimental results show that when applied to strain sensing, the OCMI-three-arm-MZI based FBG sensor is 17.5 times more sensitive compared to the two-arm interferometer based FBG sensor. And the temperature sensitivity is reduced from 371.858 KHz/°C to 1.455 KHz/°C. The prominent advantages of the sensor, including high resolution, high sensitivity, and low cross-sensitivity, make it a great potential for high-precision health monitoring in extreme environments.
一种基于光载波微波干涉（OCMI）的三臂马赫-曾德尔干涉仪（MZI）对光纤布拉格光栅（FBG）传感器进行解调的方案被提出并进行了实验验证。在我们的传感方案中，通过将三臂 MZI 的中臂分别与传感臂和参考臂干涉，产生的干涉图叠加产生 Vernier 效应，从而提高系统的灵敏度。OCMI 三臂 MZI 对传感 FBG 和参考 FBG 的同时解调为传统传感器通过级联光学元件产生 Vernier 效应所带来的交叉灵敏度问题（例如温度与应变）提供了理想的解决方案。实验结果表明，在应变传感应用中，与基于两臂干涉仪的 FBG 传感器相比，OCMI 三臂 MZI 解调的 FBG 传感器的灵敏度提高了 17.5 倍。同时，温度灵敏度从 371.858 kHz/°C 降低到 1.455 kHz/°C。该传感器具有高分辨率、高灵敏度和低交叉灵敏度等显著优点，使其非常适合在极端环境下进行高精度健康监测。
