基于多频光电振荡的高分辨率快响应海洋温盐深传感技术研究

Temperature, salinity and depth (conductivity, temperature and depth, CTD) are the three important static factors of seawater, which is an important basis for studying marine phenomena, developing and utilizing marine resources, and monitoring the changes of marine environment. This project will creatively combine microwave photonics technology and optical fiber sensing technology into marine information detection. In the context of high-resolution and high-speed detection requirements for simultaneous measurement of underwater CTD parameters, the parameter optimization of multi-frequency optoelectronic oscillator based on cascaded microwave photonics filters are researched in detailed. And its working mechanism and experimental scheme for marine CTD sensing technology are also proposed and studied in detailed. The dynamic resonance, phase noise, error analysis and sensor model of optoelectronic oscillator are established. The different types of FBG F-P filter with high finesse and narrow bandwidth characteristics is developed and encapsulated. The multi-parameter sensing characteristics and action mechanism of cascaded microwave photonics filters are also researched. Combined with the digital signal processor technology and optoelectronic oscillator based on cascaded microwave photonics filter, the experimental system for marine CTD sensing with the characteristics of high-resolution, high-speed, high signal-to-noise ratio, and simultaneous measurement for multi-parameter will be realized. The CTD simultaneous and continuous observation experiment of seawater is carry out by the proposed sensing system. This project research will provide very important references for CTD sensor with high-resolution, high-speed, and multi-parameter simultaneous measurement in ocean observation network, underwater glider and intelligent buoys.

温度、盐度和深度是海水的三大静态要素，是研究海洋现象、开发与利用海洋资源以及监测海洋环境变化的重要依据。针对水下温盐深高分辨率、快响应、多参量同时探测的需求，本课题拟创新性地将微波光子技术和光纤传感技术交叉融合到海洋信息探测上，系统深入地研究基于级联结构微波光子滤波器的多频光电振荡器结构参数优化，及其应用于海洋温盐深多参量同时测量的工作机理和实验方案。建立光电振荡器动态谐振、相位噪声、误差分析和传感模型；制备与封装不同类型高精细度、窄带宽的光纤光栅F-P滤波器件，研究级联结构多参量传感特性和作用机制；将滤波器嵌入光电振荡环结合数字信号频率解调技术，实现具有高分辨率、快速响应、高信噪比以及多参量同时测量的海洋温盐深传感实验系统，并演示系统在海水温盐深同时连续观测中的应用。本项目的研究将为海洋观测网、水下机器人以及智能浮标中高分辨率快响应温盐深同时测量传感器的发展提供重要参考。

针对海洋温度、盐度和深度等水文环境要素特征分布及变化规律开展原位、实时、高效、连续、精确的融合观测，对研究海洋现象、预测及改变未来海洋生态环境演变趋势具有重大意义。本研究将微波光子技术和光纤传感技术交叉融合到海洋信息探测上，系统深入地研究海洋温盐深等多参量同时测量的工作机理和实验方案。建立光电振荡器动态谐振、相位噪声、误差分析和传感模型；利用耦合模理论和传输矩阵法仿真分析了光纤光栅参数、干涉仪参数、光纤参数对不同类型光纤光栅和光纤干涉仪滤波器光谱特性和滤波特性影响，通过相位掩模、紫外曝光和移动扫描的刻写方法和熔融拉锥、化学腐蚀等灵活设计制作出分别对温度、压力、折射率等参数敏感且同时具有窄带滤波特性的不同类型光纤光栅和光纤干涉仪滤波器，并进行敏化和适应性封装制备，研究了级联结构多参量传感特性和作用机制。1）研制了一种由单模光纤-光子晶体光纤-无芯光纤-光子晶体光纤-单模光纤-保偏光纤光栅组成的紧凑型光纤传感器，实现了水下盐度、温度和应力的同时在线监测，具备良好的线性度和可重复性；2）设计了一种基于微波光子的毫米级海水皮表温剖面探测仪，实现0.8mm-100mm空间分辨率的海水皮表温度测量；3）设计研制了一种基于悬臂梁结构和差分光纤光栅的矢量流速传感器，实现了水下二维流速精确探测；4）设计研制了一种温度标定的水下酸碱度传感系统，通过聚乙烯醇/氧化石墨烯涂覆锥形双芯光子晶体光纤干涉仪实现水下酸碱度的高精度测量；5）设计搭建了一种基于PMFBG滤波器的微波光子温盐传感系统。采用马赫增德尔强度调制器、基于色散光纤和单模光纤的非平衡干涉仪、光电探测器、矢网分析仪构建微波光子传感系统环路，完成了温度和盐度的快速高精度测量；6）设计制备了基于光电振荡器的电流和磁场传感器，实验得到磁场灵敏度为1.33 MHz/mT，电场灵敏度152.5kHz/A。本项目研究将为海洋观测网、水下机器人以及智能浮标中高分辨率快响应多参量同时测量传感器的发展提供重要参考。