提出了一种基于普通单模光纤粗锥级联结构的马赫-曾德尔干涉湿度传感器.将两根单模光纤对芯熔融成一个粗锥, 并依次级联, 形成光纤锥-单模光纤-光纤锥-单模光纤-光纤锥结构.外界环境湿度、温度的改变使传感器的纤芯基模和包层模的光程差发生改变, 引起传感器干涉光谱发生变化.通过监测干涉谱波长和能量的变化实现对外界物理量的测量.实验结果表明, 当空气中湿度在35-95%RH范围内变化时, 传感器的湿度灵敏度为-0.065 dB/%RH, 线性度为0.997；当温度在30-80 ℃范围内变化时传感器的温度灵敏度为69.4 pm/℃, 线性度为0.998.该传感器可以避免温湿度的交叉影响, 实现单参量的同时在线区分测量.

An in-fiber Mach-Zehnder interferometer humidity sensor based on waist-enlarged fiber tapers cascade structure was proposed and demonstrated.The sensor head is formed by a taper-single-mode-taper-single-mode-taper structure through arc fusion splicing.The change of the humidity and temperature will make the optical path difference changed of the sensor core mode and cladding modes, causing interference spectral change.Through monitoring the spectra variation can determine the ambient physical quantities.The experimental results show that the humidity sensitivity of the sensor is -0.065 dB/%RH with a linearity of 0.997 in the humidity range of 35-95%RH;the temperature sensitivity of the sensor is 69.4 pm/℃ with a linearity of 0.998 in the temperature range of 30-80 ℃.This sensor can avoid the cross-sensitivity to humidity and temperature, make it a good candidate for high accuracy humidity and temperature applications.