基于弱反射光纤光栅的新型超细水听器及其拖曳线列阵技术研究

To increase the detecting distance of torpedo, UUV and other small underwater platform vehicle, a new ultra-thin towed linear array technology based on weak fiber grating hydrophone was proposed, due to the properties of weak fiber grating array that the multiplexing number in single fiber can be increased to thousands, while there are no splice points between fiber gratings, which can be directly fabricated to a optical cable by knitting, and the coherent signals of the coherent pulse reflected by fiber gratings are clear. This technology conducted research on weak fiber grating hydrophone towed line array acoustic sensing mechanism, demodulation method of coherent signals based on time division multiplexing scheme, integrated structure design of the hydrophone array, cabling of the linear arry and so on. The underwater acoustic sensing model of weak fiber grating hydrophone towed linear array was established. This project will trail-produce a 256-element weak fiber grating hydrophone towed linear array with a diameter of only 3mm. The pool experiment will be carried out to validate the theoretic model. There are three key problems to be solved: design of weak fiber grating array, high-accuracy real-time signal demodulation system resistant to environmental interference and cabling of the ultra-thin towed linear array. These studies provide necessary theoretic and technical support for the development on increasing array aperture, lowing operating frequency, increasing hydrophone element number and breaking the bottleneck problem for the installation of the towed line array on torpedo, UUV and other small underwater platform. This research explores a new technical way for the leapfrog development of topedo, UUV and other underwater special equipment.

为提高国内鱼雷、UUV等水下小平台航行器的探测距离，本课题基于弱反射光纤光栅阵列具有的光栅单纤复用数多达数千个、光栅间无熔接点连接可直接编织成缆、光栅对的相干脉冲激光反射光的相干信号清晰等特性，提出了一种基于弱反射光纤光栅水听器的全新超细拖曳线列阵技术，通过开展基于弱反射光纤光栅水听器拖曳线列阵的工作机理、时分复用相干信号解调技术、弱反射光纤光栅水听器结构及其阵列的一体化设计和成缆方法等研究，建立弱反射光纤光栅水听器拖曳线列阵水声探测模型，研制一条缆径仅为Φ3mm的256元轻质拖曳线列阵样阵和信号解调样机，开展湖上试验验证研究。重点解决弱反射光纤光栅阵列设计、高精度低噪声实时信号解调和超细拖曳线列阵成缆工艺等难题，为增大基阵孔径、降低工作频率、增加水听器阵元数量、突破鱼雷、UUV等水下小航行器拖线阵的适装性这个瓶颈问题提供了必要的理论和技术支撑，为鱼雷、UUV的跨越式发展。

为提高鱼雷、UUV等对安静型潜艇的探测距离，针对水下目标10Hz以下的辐射噪声难以降低这一特征，利用甚低频“窗口”进行水中目标探测，是实现深远海对安静型潜艇远程探测的有效技术手段。为降低工作频率，必然增大基阵孔径、增加水听器阵元数量，并需解决鱼雷、UUV等拖线阵的适装性这个瓶颈问题，急需发展应用于水下小航行器的甚低频声探测新技术。.本项目基于弱反射光纤光栅阵列具有的单纤复用光栅数多、光栅间无熔接点、光栅对的反射脉冲激光相干信号清晰等特性，提出了提出了一种基于弱反射光纤光栅的新型超细水听器及其拖曳线列阵新技术，针对其拟解决的关键科学问题进行了探索研究，完成的主要研究工作如下：.（1）完成了基于弱反射光纤光栅水听器水声探测机理和水声传感模型研究，建立了基于均匀体应力作用假设的弱反射光纤光栅水听器声压灵敏度模型；.（2）优化设计了弱反射光纤光栅传感阵列参数，完成了阵列实际损耗小于0.4dB/km的弱光纤光栅水声传感阵列裸纤制备，研制出弱反射光纤光栅间隔为50m的水听器样品，其声压灵敏度大于-160 dB re rad/uPa； .（3）提出了一种基于参考传感器的光纤水听器干涉信号强度补偿方法，突破了基于匹配光纤干涉仪和3×3耦合器的弱反射光纤光栅水听器信号解调技术，研制出256基元水听器拖线阵信号解调样机；.（4）建立了弱反射光纤光栅水听器拖线阵二次涂覆增敏理论模型，突破了该拖线阵成缆和增敏一体化关键技术，试制出缆径分别为0.4mm、0.9mm、2mm和7.5mm的256元基元弱反射光纤光栅水听器拖曳线列阵，基阵工作带宽5Hz～10Hz；.（5）对不同材料、直径、增敏结构的细线型弱反射光纤光栅水听器进行了相关试验测试与验证。.弱反射光纤光栅水听器在甚低频工作带宽灵敏度响应良好，弱反射光纤光栅阵列内部产生的时分复用串扰明显低于普通反射率光栅，本项目研究成果为深远海安静型潜艇的甚低频探测探测提供了新的技术手段，填补了国内毫米直径超细光纤水听器和甚低频超细拖曳线列阵研究空白，具有重要军事意义。