基于空芯光纤的集成式全光纤法-珀干涉式湿度传感器

Miniature Humidity Sensor Based on All-Fiber Fabry-Pérot Interferometer Formed by Hollow Core Fiber

利用空芯光纤制作的法布里-珀罗(Fabry-Pérot,F-P)干涉传感器具有较低的温度敏感性,由于传感器干涉光光程差与空芯光纤制作的F-P干涉腔腔内介质折射率有直接依赖关系,提出在空芯F-P干涉传感器的腔内填充一种具有较强吸水性的新型纳米复合水凝胶从而构成一种温度低敏感的微型湿度计。当水凝胶通过吸收空气中的水蒸汽而使自身的折射率发生变化时,就会导致F-P腔干涉光的光程差发生变化,通过检测这一光程差的变化就可实现对环境相对湿度的测量。实验结果表明,填充自制的水凝胶,在38%～98%的相对湿度变化范围内,传感器的光程差从608.7180μm变化到了604.0488μm,在水凝胶折射率变化范围内,其光程差与相对湿度的灵敏度为77.82nm/(1%)。

A highly sensitive humidity sensor based on Fabry-Pérot（F-P）interferometer which is formed by hollow core fiber with low sensitivity to temperature is realized.Because the optical path difference of interferential cavity depends on the cavity length and the refractive index of the media which is filled in the F-P cavity.The F-P sensor is filled with a novel nano-composite hydrogel with a strong water capacity.It is realized that the humidity can be measured by measuring optical path difference of the sensor when the refractive index of hydrogel changes due to absorbing water vapor in the air substantially.The experimental results show that the optical path difference changes from 608.7180 μm to 604.0488 μm when the surrounding humidity varies in the range of 38%~98% and the sensitivity of optical path difference versus the relative humidity is 77.82 nm/（1%）.