基于反馈环全光纤干涉的一种新型光声检测方法

A New Photoacoustic Detection Method Based on All-Fiber Interferometer System with Feedback Loop

提出了一种光声检测的新方法,这种检测方法的拾音器部分主要采用了单模光纤,通过带有反馈环的全光纤干涉系统来放大光声信号.气体吸收腔则采用了在气体吸收红外指纹区具有较宽低损窗口的空芯光纤作为谐振光声池.基于光纤应变传感器的基本原理和弹光效应推导出光声换能公式,并搭建了整个实验系统进行测量,得到干涉信号的强度与声信号衰减趋势相同.根据实测结果进行了干涉信号强度与声信号强度的指数衰减曲线的拟合,得到了平均为0.98的较高的拟合度.比较了不同内径的空芯光纤光声池的实验结果,发现内径较大的光声池灵敏度更高.

An alternative method for photoacoustic detection,based on all-fiber interferometer system with feedback loop,is proposed.An experimental system was established by using hollow-core optical fiber as simulative photoacoustic（PA）cell.The detection was made of a single mode fiber coupling to one end of PA cell and a Sagnac interferometer detection scheme was used. Theoretical analysis based on optical fiber strain sensors and photoelastic effect was conducted.Measured results for various PA cells at different acoustic signal intensity showed agreement with that of the interference signal.Comparison experiments for PA cells with different inner diameters showed that PA cell with larger diameter is of high sensitivity.