一种基于光纤内马赫-曾德尔干涉仪的低频声传感方案  

A low-frequency acoustic sensor scheme based on an in-fiber Mach-Zehnder interferometer

作　　者：胡晓 田晶 田佳俊 陈富城 陈小杰 杨诗宇 江阳 HU Xiao;TIAN Jing;TIAN Jiajun;CHEN Fucheng;CHEN Xiaojie;YANG Shiyu;JIANG Yang(College of Physics,Guizhou University,Guiyang 550025,China)

机构地区：[1]贵州大学物理学院,贵阳550025

出　　处：《物理学报》2025年第9期97-103,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61801134,61835003);贵州大学审核评估专项(批准号:GDSHPG2023007);贵州大学课程体系改革项目(批准号:XJG2024045)资助的课题.

摘　　要：提出了一种基于光纤内马赫-曾德尔干涉仪结构的低频声传感方案,其中传感光纤是由多模-超高数值孔径-多模光纤焊接级联而成的微型马赫-曾德尔干涉仪,可有效提高光纤弯曲灵敏度;然后将该干涉仪结构与聚对苯二甲酸乙二酯换能膜片进行组合,使得传感光纤在受到声压作用时与膜片同步产生曲率变化,间接增大了光纤接收声场的面积.文章推导了该系统的声传感理论,并通过实验进行了验证,得到传感系统在65 Hz处信噪比约为57 dB,最小可探测声压为267.9;μPa/Hz^(1/20)在50-500 Hz的频率范围内,对声波有较好响应,信噪比均在40 dB以上,信号较平坦.该方案可显著提升传感系统声响应能力,实现对低频声波的有效检测,且具有制作简单、成本低的特点,在声波探测相关应用领域具有较大的发展潜力.In this work,a low-frequency acoustic sensing scheme is proposed based on the structure of in-fiber Mach-Zehnder interferometer,in which the refractive index difference between fiber core and cladding is used to form a miniature Mach-Zehnder interferometer through fusion splicing of specialty optical fibers in a multi-mode-ultra-high numerical aperture-multi-mode configuration.This design achieves modal recombination between cladding and core modes,thereby effectively enhancing fiber bending sensitivity.The interferometer structure is then combined with a polyethylene terephthalate(PET)transducer diaphragm,enabling the sensing fiber to undergo curvature changes synchronously with the diaphragm under sound pressure,thereby indirectly increasing the area over which the fiber receives the acoustic field.When external acoustic pressure induces bending modulation on both the sensing fiber and transducer diaphragm,the differential strain distribution between the fiber cladding and core generates an optical path difference.This manifests itself in interference spectrum shifts,enabling the effective detection of low-frequency acoustic signals through demodulating the spectrum variations.In the paper,the theoretical framework for the acoustic sensing system is derived and validated experimentally.The results show that at 65 Hz,the system achieves a signal-to-noise ratio(SNR)of 267.9μPa/Hz^(1/2) approximately 57 dB and a minimum detectable sound pressure of at 65 Hz.In a frequency range of 50–500 Hz,the system exhibits good acoustic response,with an SNR consistently above 40 dB and a relatively flat signal output.This scheme significantly enhances the acoustic response capability of the sensing system,enabling the effective detection of low-frequency acoustic waves.Additionally,it features simple fabrication and low cost,showing great potential for the development of acoustic wave detection applications.

关 键 词：光纤传感 马赫-曾德尔干涉仪 声传感器 声波测量 

分 类 号：O436[机械工程—光学工程]