基于单纤拉锥M-Z干涉仪的折射率传感器

A Refractive Index Sensor Based on Single Fiber Taper M-Z Interferometer

在单模光纤中级联两个对称缓锥,中间段去除涂覆层,包层作为传感臂对外界折射率敏感,实验上形成M-Z（马赫-曾德尔）干涉仪。对锥区光场进行分析,当锥腰半径为25μm时,光纤内模场半径达到最大值,约为14.8μm。当锥形光纤锥腰半径为12.5μm、过渡区为5 mm、锥间隔为131 mm时,耦合与合波效果最佳,此时传感臂可检测的酒精浓度范围为0-100%,折射率和波长偏移存在很好的线性关系,灵敏度为-120nm/RIU。该传感器具有插入损耗低、性能稳定和抗干扰能力强等优点,可应用于酒厂酒精度检测和水质监测等领域。

In this paper,we cascade two symmetrical slow tapers in a single-mode fiber and remove the coating between two ta-pers,which achieve a Mach-Zehnder（M-Z）interferometer.The cladding is act as a sensing arm,which is sensitive to the re-fractive index in the outside world.Through the analysis of the optical field evolution of taper region,mode field radius will reach maximum value of 14.8 μm when fiber taper has a radius of 25 μm.When taper waist radius is 12.5 mm,transition re-gion is 5 mm,and taper region interval is 1 3 1 mm,the effect of coupling and waving is best.The sensing arm can detect alco-hol concentration in the range of 0-100%,which has a good linear relationship between refractive index and wavelength offset with detection sensitivity of -120 nm/RIU.The sensor has advantages of low insertion loss,stable performance and strong anti-interference capacity,which can be applied to areas such as distillery and water quality monitoring.