π相移光纤光栅对超声波致非均匀应变场的传感特性  

Response of π-phase-shifted fiber Bragg grating to inhomogeneous strain fields caused by ultrasonic wave

作　　者：安秉文 吴先梅[1,2] 李子琪 李斐然 AN Bingwen;WU Xianmei;LI Ziqi;LI Feiran(Institute of Acoustics,Chinese Academy of Sciences,Beijing 100190;University of Chinese Academy of Sciences,Beijing 100049)

机构地区：[1]中国科学院声学研究所,北京100190 [2]中国科学院大学,北京100049

出　　处：《声学学报》2023年第1期119-127,共9页Acta Acustica

基　　金：国家自然科学基金项目(11674351)资助。

摘　　要：π相移光纤光栅用于水中超声传感时,超声波沿光纤轴向入射和垂直光纤入射时的传感波形及幅度显著不同。针对这一现象,本文建立了基于光学传递矩阵的光纤光栅声传感理论模型,计算了超声波分别沿轴向和沿垂直方向入射时π相移光纤光栅中的非均匀应变场分布,进而分析了光谱偏移,揭示了两种入射角度下π相移光纤光栅的传感特性与声传播导致的应变场分布相关,并通过实验进行了验证。结果表明,两种入射角度产生的不同的非均匀应变场分布对π相移光纤光栅的传感特性影响明显。超声波垂直入射时的传感波形和幅度均优于轴向入射,且π相移处对传感有显著作用。当入射位置远离π相移处时,垂直入射的响应也明显降低。本研究可为π相移光纤光栅超声传感的机理分析提供参考。Aiming at different sensing characteristics on waveform and amplitude of a π-phase-shifted fiber Bragg grating under axially and vertically incident ultrasonic wave in water,a fiber Bragg grating ultrasonic sensing model is established based on transfer matrix method.Inhomogeneous strain fields along grating under axially and vertically incident ultrasonic wave are calculated,which helps to analyze sensing characteristics of π-phase-shifted fiber Bragg grating under above two situations by using further wavelength shift results.Experiments are then performed to verify analytical results.Results show that the sensing characteristics of π-phase-shifted fiber Bragg grating are obviously affected by different inhomogeneous strain field distributions under two incident angles.Both sensing waveform and amplitude under vertically incident ultrasonic wave perform better than axially,and π phase shift plays a significant effect on sensing characteristics.With the increase of the distance between incident position and phase shift point,the response under vertically incident ultrasonic significantly declines.The research provides guidance for analyzing ultrasonic sensing mechanism of π-phase-shifted fiber Bragg grating.

关 键 词：非均匀应变场 传感特性 π相移光纤光栅 垂直入射 光学传递矩阵 入射角度 声传播 光谱偏移 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]