一种基于大角度倾斜光纤光栅包层模的低频声传感方案  

A low-frequency acoustic sensing scheme based on cladding mode of large-angle tilted fiber Bragg grating

作　　者：左一武 田晶 杨清 胡晓 江阳 Zuo Yi-Wu;Tian Jing;Yang Qing;Hu Xiao;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》2023年第12期170-176,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61801134,61835003)资助的课题。

摘　　要：利用倾斜光纤光栅在发生弯曲时其存在的多种纤芯-包层模式耦合方式容易发生改变,进而使其光谱特征发生明显变化的特点,提出并验证了一种基于大角度倾斜光纤光栅包层模的低频声传感方案.将倾斜光纤光栅与设计的聚对苯二甲酸乙二酯(PET)换能膜片及腔体结构相结合,得到了一种有效的低频声传感系统.该换能膜片在被测声波信号作用下产生振动,使固定在膜片表面的倾斜光纤光栅发生周期性动态弯曲,引起倾斜光纤光栅的包层模式光谱发生周期性漂移,最后采用边缘滤波法进行解调,实现低频被测声波的有效探测.实验结果显示,该传感方案可以在45—220 Hz范围内实现高灵敏度声波探测,在传感系统固有频率附近54 Hz处获得最大声灵敏度115.88 m V/Pa,且最小探测声压为539.2μPa/Hz1/2.该传感方案具有灵敏度高、重复性好、结构简单、容易加工等优势,在低频声探测等相关应用领域具有较大的发展前景.A novel low frequency acoustic sensor based on the cladding mode of large-angle tilted fiber Bragg grating(TFBG)is proposed and verified in this work.It mainly uses the characteristic that the coupling mode of the core and cladding mode in TFBG is easy to change when the TFBG experiences micro-bend,which will finally causes a dramatic drift in the spectrum.By combining a large-angle TFBG with the designed polyethylene terephthalate(PET)transducer diaphragm and cavity structure,an effective low-frequency acoustic sensing system is obtained in this work.Under the action of applied acoustic wave,the transducer membrane will have periodic vibrations,which will makes the fixed TFBG dynamically bend,directly leading to a wavelength shift of the cladding mode spectrum.The experimental results show that the sensing system can achieve high-sensitivity acoustic detection in a frequency range of 45-220 Hz,and a maximum acoustic pressure sensitivity of 115.88 mV/Pa at 54 Hz.Moreover,the minimum detection sound pressure can achieve 539.2μPa/Hz1/2@54 Hz.Therefore,the sensor has the advantages of high sensitivity,good repeatability,simple structure,easy processing,etc.It has a great development prospect in the low-frequency acoustic detection related application fields.

关 键 词：光纤声传感 倾斜光纤光栅 模式耦合 动态弯曲 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]