本文设计并制作了一种基于光纤马赫-曾德尔干涉仪(Mach-Zehnder interferometer,MZI)的光纤液位温度传感器。该结构是由熔接在单模光纤(single-mode fibers,SMFs) 之间的一段无芯光纤(no-core fiber,NCF)和一段多模光纤(multi-mode fiber,MMF)拼接而成。由于周围环境液位和温度的变化会导致干涉仪传输光模式改变,进而引起干涉光谱条纹移动。通过检测干涉光谱的两个谷值波长的漂移情况,便可获得液位和温度响应的灵敏度,利用灵敏度系数矩阵可实现对液位和温度的同时测量。研究表明,当液位升高时,干涉光谱发生红移；在0—36 mm液位变化范围 内,其最大液位响应灵敏度为208.38pm/mm。当温度升高时,干涉光谱依然保持红移现象；在30—70 ℃温度变化范围内,其最大温度响应灵敏度为29.67 pm/℃。该传感器结构具有灵敏度高、测量范围大、制造简单、成本低以及液位温度同时测量等优点,在传感领域具有应用潜力。

A fiber liquid level temperature sensor based on fiber Mach-Zehnder interferometer (MZI) is designed and fabricated in this paper.The structure is composed of a no-core fiber (NCF) and a multi-mode fiber (MMF) fused between single-mode fibers (SMFs).The change of ambient liquid level and temperature will lead to the change of optical transmission mode of the interferometer, and then cause the movement of interference spectrum fringe.The sensitivity of liquid level and temperature response can be obtained by detecting the drift of wavelength of two valleys in the interference spectrum. The sensitivity coefficient matrix can be used to measure liquid level and temperature simultaneously.The results show that the interference spectrum is red shifted when the liquid level rises.The maximum liquid level response sensitivity is 208.38 pm/mm in the range of 0—36 mm level variation. When the temperature increases,the interference spectrum still keeps red shift.The maximum temperature response sensitivity is 29.67 pm/℃ in the range of 30—70 ℃.The sensor structure has the advantages of high sensitivity,large measuring range,simple manufacturing,low cost and simultaneous measurement of liquid level temperature, etc.,which has the potential application in the sensing field.

陕西省重点科学研究计划项目(2020JS122)和西安石油大学研究生创新基金(YCS22221073)资助项目