高环境稳定性光纤MEMS声波传感器研究

Optical fiber acoustic sensors have been attracted considerable research interests for its potential applications in industry and military because of their particular characteristics, such as high sensitivity, simple structure, and resistance to electromagnetic interference. The ones combined with MEMS technology have more advantages, such as small size, high accuracy, varied design, and benefit to sensor-array integration. Among the optical fiber acoustic sensors, interferometric ones possess higher sensitivity, but always suffer from serious environment interference, which lowers the sensors’ stability and limits their applications. To solve this problem, we develop an interferometric acoustic sensor with high stability. We design a MEMS structure based on diffraction grating as the acoustic sensitive module, and an innovative signal demodulation method based on the inverted light from two diffraction level of the grating. The project includes: researching the MEMS structure based on diffraction grating for acoustic detection; researching the signal demodulation method based on the inverted light from the grating for high stability against environmental interference; designing the structure of the acoustic sensor; researching the MEMS processes to manufacture the sensors; building the test platform for analyzing the characteristic of the sensor. The development of the proposed optical fiber acoustic sensor would provide the basis for the acoustic sensors with high performance and their real applications.

光纤声波传感器具有灵敏度高、结构简单、抗电磁干扰等优点，是继电容式和电压式声传感器之后的新一代探测设备，在工业、军事等领域具有广泛的应用前景。结合MEMS技术的新型光纤声波传感器又具有尺寸小，精度高，设计灵活，便于阵列集成的优势。干涉式光纤声波传感器具有较高的灵敏度，但环境干扰造成的工作点漂移问题降低了其稳定性，严重制约着实用化发展，对此还没有非常适合应用的解决方案。针对这一问题，本项目提出结合端面耦合光栅干涉腔MEMS声传感结构和光栅双衍射级次反相信号解调方法的新型方案。项目主要内容包括：研究端面耦合光栅干涉腔MEMS结构的声传感机理；研究基于光栅双衍射级次反相信号解调的环境稳定机制；通过模型仿真，优化声波传感器结构设计；通过MEMS工艺流程设计与关键工艺研究，实现声波传感器结构；搭建测试平台，进行声波传感器综合性能测试。通过本项目的实施将为高性能光纤声波传感器的研制及实用化奠定基础。

空气声探测在军事、工业、气象环境等领域都具有广泛且重要的应用。新型的基于光学检测方法的声传感技术以高灵敏度、非接触式响应、抗电磁干扰、便于组网等优势受到越来越多的关注。其中光干涉型检测方法以其突出的高灵敏度优势尤其适合高精度声传感技术发展。当前应用环境因素干扰造成工作点漂移导致的传感稳定性问题是限制光干涉型声传感技术实用化发展的一个关键问题。本项目重点针对这一问题，结合光栅干涉型传感机理和基于光栅双衍射级反相特征信号的高稳定传感机制，研究基于MEMS光栅干涉腔的高稳定性声传感技术。本项目研究了引入光栅衍射效应的光干涉型声传感机理，构建了核心传感结构模型；基于得到的光栅双衍射级反相特征信号，针对环境因素干扰导致的工作点偏移问题研究高稳定声传感机制，同时考虑初始工作点偏离以及光源波动等干扰问题，建立了基于光栅双衍射级反相信号的高稳定性声传感信号解调方法；在理论研究基础上，进行了高温度稳定性的小腔长MEMS光栅干涉腔声传感结构优化设计，并通过其制作流程设计和关键工艺优化制得了高性能的MEMS声传感元件；通过匹配光纤检测光路和检测电路实现了声传感器系统样机，并搭建测试平台对声传感器的综合性能进行了测试。本项目所研制的声传感器具有高灵敏度（＞150mV/Pa）和高温度稳定性（50℃范围内变化＜5%），同时建立的光栅双衍射级反相信号解调方法有效解决了高强度声信号检测和工作点偏离造成的声信号检测失真问题。本项目对新型高性能光干涉型传感技术进行研究，研究成果以高集成高稳定性的MEMS传感元件匹配对光检测系统要求较低的高稳定性光栅干涉光信号解调方法实现了高稳定性声传感技术，适应当前军事信息化发展以及民用便携设备发展对小型化、集成化、智能化声传感器的应用需求，具有重要的应用价值。