双模耦合光纤激光微腔复合域光学特性及其用于多元参量分布式传感的基础研究

The program investigates optical characteristics of double-modes coupled fiber micro-cavity in hybrid domains and its application in multi-parameters and distributed sensing technology, aiming at the satisfying the requirement of curing process monitoring of composite materials. Based on the research achievements of last program, we propose novel schemes including structure design, sensing principle and fabrication technique. The main research contents are as follows: 1)Optical characteristics of fiber micro-cavity in hybrid domains and its multi-parameters sensing principle;2)Fabrication technique of fiber micro-cavity;3) High precision detection principle based on coupling mechanism between double-wavelength lasing modes generated in active fiber; 4）High precision detection principle of multi-parameters based on coupling mechanism between orthogonal polarization modes；5）Distributed sensing principle based on hybrid multiplexing mechanism;6)Application in curing process monitoring of composite materials.The major innovation includes the following aspects:1）The fiber micro-cavity integrates the sensitive characteristics of resonate modes of grating and evanescent fields of micro/nano fiber，and thus simultaneous multi-parameters sensing could be realized assisted by optical analysis in hybrid domains;2）The micro-cavity in polarization-maintaining active fiber will enhance the modes lasing and coupling effect, resulting in great sensitivity increase；3）The one-step fabrication method of fiber micro-cavity posses the advantages of easy manipulation and high reliability. The research achievements could be applied to refractive index, temperature and pressure monitoring during the curing process of composite materials, thus improving the quality of them.

本项目在青年科学基金研究基础上从结构设计、传感机理和制备工艺等方面创新，针对复合材料固化过程监测需求，研究双模耦合光纤激光微腔复合域光学特性及多元参量分布式传感技术。主要内容：1）光纤谐振微腔复合域光学特性及多元参量敏感机理；2）光纤微腔制备工艺；3）基于双波长模式耦合有源光纤微腔的高精度检测机理；4）基于正交偏振模式耦合有源光纤微腔的多元参量高精度检测机理；5）基于多域复用的分布式传感机理；6）复合材料固化过程中多元参量的分布式传感监测应用。主要创新点：1）光纤微腔结构融合光栅谐振模式和微纳光纤倏逝场分布的敏感特性，结合复合域光学特性分析实现多参量同步传感；2）有源保偏光纤谐振微腔增强模式激射和耦合作用，极大提高检测灵敏度；3）光纤微腔的一次成型制备方法操作简单、可靠性高。研究成果可用于复合材料固化过程中各个部位折射率、温度、压力等多参量的高精度分布式监测应用，提高其固化成型质量。

本项目面向复合材料固化成型质量控制过程中各个部位折射率、温度、压力等参量的实时监测需求，研究基于双模耦合光纤微腔复合域光学特性的多元参量分布式传感技术。针对光纤微腔增敏机理、多元参量感知机理、多域混合复用扩容机制等科学问题，开展创新研究。主要研究内容及成果包括：（1）全微纳光纤集成谐振微腔设计、制备与增敏机理。提出“打结-组装”方法，设计并实现了微纳光纤斜8字和θ结构的小型化传感单元，利用光学游标效应显著提升折射率感知灵敏度至6523nm/RIU，线性度高达0.9992，测量精度达到10-7RIU；（2）单根特种微纳光纤的光学特性和传感特性。针对基于偏振模式耦合的D型微纳光纤和基于模间耦合的多模微纳光纤，理论分析发现其灵敏度曲线存在转折点，证明折射率/温度灵敏度在转折点附近可达到±∞，并在实验上分别实现9951.613 nm/RIU和 -0.989 nm/℃的折射率和温度灵敏度；（3）基于单根多模微纳光纤的多参量传感机理。基于多模微纳光纤的模间干涉，结合双臂干涉、芯包模干涉、干涉光强调制等光耦合机制，提出了三种折射率/温度双参量传感方法，分别实现了高灵敏、单线式、反射式探针结构的多参量传感器；（4）基于光纤F-P微腔多域复用的分布式多参量传感机理。提出光纤光栅与微纳光纤结合的MFPI微腔结构及“单模光栅刻写——中间熔融拉锥”制备方法，实现折射率/温度的双参量传感，检测精度达到10-6RIU和0.1℃；结合波分复用技术，实现1m线度上最小空间分辨率10cm的分布式双参量传感；基于弱光栅FP微腔的混合波分和频分复用技术，结合弹性材料压力增敏，实现高灵敏、大容量的分布式压力传感，检测精度优于10-5N/mm；（5）复合材料固化过程中参量分布式传感监测。将连续FP微腔分布光纤植入液态硫化硅橡胶材料中，通过光谱追踪实现复合材料固化过程监测。项目研究成果不仅为复合材料固化成型过程监控提供了创新手段，还可用于智能蒙皮、生化痕量检测等领域，具有重要的科学意义和应用前景。