分布反馈光纤激光水听器封装结构的设计

摘要

针对分布反馈式(DFB)光纤激光器用于水声探测时频响曲线起伏较大的问题,设计了一种开孔套管式封装结构.通过对DFB激光器的封装,使其张紧后被聚氨酯固定于开孔套筒的中心轴线上,利用开孔套管的保护作用以及施加于光纤激光器两端的拉力来抑制水声探测过程中频响曲线的起伏.基于有限元软件ANSYS对封装结构的动态特性进行了数值仿真计算,然后加工制作了开孔套管结构封装的DFB光纤激光水听器原型样品,并利用振动液柱法进行了测试.试验结果显示,DFB光纤激光水听器在20～800 Hz的声压灵敏度达到-131 dB左右,灵敏度起伏不高于±1.5 dB,表明通过该封装结构的保护及聚氨酯的张紧作用,有效抑制了频响曲线的起伏,改善了DFB光纤激光水听器的水声探测性能.%To reduce the fluctuation of frequency response of a Distributed Feedback (DFB) fiber laser used in underwater sound detection, an encapsulated structure with orifices was designed. With the encapsulated structure, both ends of the DFB fiber laser were fixed along the axes of the structure by the tension of polyu-rethane,and the fluctuation of mid-frequency response was restrained. The dynamics of the encapsulated structure was numerically analyzed with ANSYS, and a prototype of the new kind of hydrophone based on the structure was produced and tested with the vibration fluid column method. The results show that the fluctuation of frequency response of the DFB fiber laser is restrained effectively from 20 Hz to 800 Hz, and the a-coustic pressure sensitivity reaches to ?31 dB with the fluctuation less than +1. 5 dB. These results demonstrate that the performance of the DFB fiber laser hydrophone has been improved by the protection of the encapsulated structure and the tension of polyurethane.