基于微波光子技术的高分辨率和高精度多参量光纤传感解调研究

随着新一代物联网、智能制造和人工智能等技术的发展，作为信息感知核心单位的传感器迎来了快速发展期。光纤传感器因设计灵活、损耗低、重量轻和具有抗电磁干扰能力等优点被广泛应用于隧道安全监测，航空航天以及生物医学工程等领域。光纤传感器经过近几十年的发展，目前已相对比较成熟，而其解调技术目前仍然以光谱探测解调法为主；但随着光纤传感器应用领域的拓展，对其解调分辨率和解调速度提出了更高的要求，因此需要设计新的光纤传感解调方案。基于微波光子技术的光纤传感解调方案具有高分辨率和高速解调的优点，近年来受到广泛关注。但该技术在对在线型光纤干涉仪传感器的高分辨率解调和复用解调方面，以及同时针对不同类型光纤传感器多参量传感解调方面，还未有相关的解决方案。另外，现有的基于微波光子光电振荡器的光纤传感解调系统还存在稳定性差，测量精度需要进一步提高的问题。

本文主要以微波光子技术中的滤波器和光电振荡器为核心，面向节点式光纤传感器，开展了高分辨率、高精度和多参量的光纤传感解调研究，主要研究内容如下：

1. 针对现有对在线型光纤马赫增德尔干涉仪（MZI）传感器解调分辨率低以及无法直接在光谱域上对其进行复用解调的问题，本文提出了基于微波光子单通带滤波器的高分辨率传感解调方案。在该方案中，首先基于具有抗弯曲损耗特性的环芯光纤设计并制作了单模-无芯-环芯-无芯-单模（SMF-CLF-RCF-CLF-SMF）结构的在线型MZI传感器。然后，将设计的在线型MZI传感器输出的干涉谱的自由频谱范围（FSR）的变化通过微波光子单通带滤波器系统转换为微波域的频率变化，进而实现了对曲率的高分辨率测量，测得曲率分辨率高达 m-1。进而通过对两个在线型MZI传感器的并联解调验证了系统的复用能力。

2. 在上述研究基础上，更进一步地实现了基于微波光子单通带滤波器的光学无线高分辨率传感解调，进而扩展了该解调技术以及光纤传感器的应用场景。光学无线传输功能主要通过45度倾斜光纤光栅的辐射特性来实现。实验中分别对应变、温度等进行了测量，测得的应变灵敏度是1.26 ，分辨率为  ；温度灵敏度是-10.3625 MHz/oC，分辨率高达 oC。并进一步提出了改进后的基于三抽头型微波光子滤波器传感解调方案，使得系统除了具备传感检测能力之外，还具备对传感器自身波长进行识别与判定的潜力。

    3. 针对现有微波光子光纤传感解调技术不能实现对不同类型的多传感器同时解调的问题，本文提出了一种基于微波光子非均匀间隔滤波器的多参量传感解调方案。该方案把微波光子滤波器的幅频响应和相频响应上各自携带的传感信息量通过傅里叶逆变换的方式合并转换到时域脉冲上，克服了以往基于微波光子单通带滤波器的解调方案只能利用强度或波长等单一参数表征传感信息的限制。实验中，使用该解调方案对三类不同类型的光纤传感器同时进行了传感解调，实现了四种物理参量的测量，测得的扭转度灵敏度是 a.u/degree，侧向压强灵敏度为6.1039 ps/kPa，横向载荷灵敏度是 a.u/gram，温度灵敏度是5.1497 ps/oC。

    4. 为了提高基于微波光子光电振荡器的光纤传感解调系统的稳定性，进而实现高精度的测量，本文提出了一种基于双环型光电振荡器的光纤传感解调方案。该方案通过在光电振荡腔内增加一个短的光纤环路来实现对整个振荡器腔内的模式进行“滤波”，有效解决了因腔内模式过多、增益竞争激烈而导致的频率不稳定的问题。通过把传感探头嵌入在光纤环形激光腔内，提高了光载波信号质量，为系统性能提供了保证。实验结果表明，双环系统的相位噪声是-130.86 dBc/Hz@10 kHz，比单环系统低了6.2 dB；双环传感系统的输出频率波动量是0.277 ppm，是目前已报道的最小测量值。

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