基于超弱光纤光栅的声波传感探头增敏方法研究

Research on Sensitizing Method of Acoustic Sensor Probe Based on Ultra-weak Fiber Bragg Grating

针对光纤直接探测声波时灵敏度低的问题,提出一种超弱光纤光栅缠绕式薄壁圆筒的声波传感探头增敏方法。理论分析了薄壁圆筒半径、壁厚、弹性模量等参数对光纤探头声增敏的影响,仿真分析了光纤缠绕方式对探头谐振频率的影响,优化设计了弹性管式探头的结构。搭建了基于超弱光纤光栅声波传感系统,并对探头的声敏特性进行了测试。实验结果显示,探头的声压灵敏度最高可达到6.39746 rad/Pa(-103.8798 dB re rad/μPa),在1000~2000 Hz的平均声压灵敏度为3.30341 rad/Pa(-109.6208 dB re rad/μPa);相较于未增敏的裸光纤,探头的平均声压灵敏度提高了约31 dB。

Aiming at the problem of low sensitivity when optical fiber directly detects acoustic waves,an acoustic sensor probe sensitizing of thin-walled cylinder based on ultra-weak fiber Bragg grating was proposed.The effects of thin-walled cylinder radius,wall thickness,elastic modulus and other parameters on the acoustic sensitization were analyzed theoretically,then the influence of fiber wrapping patterns on the resonant frequency was analyzed through simulation,and the elastic tube probe structure was optimized.The acoustic sensing system based on ultra-weak fiber grating was built and the acoustic sensitivity of the transducer was tested.The experimental results show that the acoustic pressure sensitivity can reach up to 6.39746 rad/Pa(-103.8798 dB re rad/μPa),and the average acoustic pressure sensitivity during 1000~2000 Hz is 3.30341 rad/Pa(-109.6208 dB re rad/μPa).Compared with the bare fiber loop,the average acoustic pressure sensitivity is increased by about 31 dB.