【作者】 李萍；

【导师】 刘云；

【作者基本信息】 大连理工大学 ， 光学工程（专业学位）， 2020， 硕士

【摘要】 与传统的湿度传感器相比,光纤湿度传感器具有体积小、耐高温、抗电磁干扰、响应速度快、结构紧凑、制作工艺简单等优点。本文首先对传统的光纤湿度传感器的研究现状和发展趋势进行了介绍,此后将光纤倏逝场传感技术与氧化石墨烯二维材料相结合,设计并制作了一种基于微毛细管和氧化石墨烯(GO)薄膜的高灵敏度倏逝场型光纤湿度传感器。主要研究内容如下:本文提出了一种基于熔融石英毛细管与光纤混合结构的新型倏逝场型传感器。该传感器通过光纤熔接机将切割平整的普通单模光纤熔接在毛细管端面上制作而成,传感区域总长度仅为1.5mm。当光由导入光纤进入毛细管壁后会激发多种模式,且不同的模式间相互干涉,该传感结构的输出信号呈现出清晰的干涉光谱。作为一种新型二维材料,氧化石墨烯表面修饰有大量的含氧官能团,具有优良的亲水性,使其在湿度传感方面具有独特的优势。本文采用氧化石墨烯材料对所提出的光纤倏逝场型传感器进行修饰。首先采用氢氧化钠溶液对氧化石墨烯溶液进行PH调节,然后通过浸涂法在毛细管外壁上分别涂敷1、3、5个周期的氧化石墨烯层,对氧化石墨烯与毛细管壁的相互作用所激发的倏逝场进行了实验和理论研究。在温度为25℃、相对湿度为30-70%的条件下,对传感器的性能进行了测试。实验结果表明,随着氧化石墨烯涂层致密程度的增加,传感器对湿度的敏感性也随之提高。此外,本文研究了氧化石墨烯涂层与毛细管长度对传感器湿度响应的影响,考虑到氧化石墨烯薄片的消光、透射损耗和毛细管壁的反射次数,对毛细管的长度进行了优化,以获得最佳的光谱响应。本文利用浸涂镀膜的方法将多层薄膜技术与光纤传感技术结合,传感区域采用微毛细管代替传统的光纤,得到的基于氧化石墨烯的微毛细管光纤倏逝场传感器表现出对湿度的灵敏响应,其透射光谱具有锐利的波峰和波谷,传感信号具有良好的信噪比。且由于氧化石墨烯涂层的周期是可控的,该传感器具有可调谐的湿度灵敏度。该湿度传感器结构紧凑、所用的制备方法简单、制备成本低,有望在环境传感和健康监测的全光纤网络中得到应用。更多还原

【Abstract】 Compared with the traditional humidity sensor,the fiber optic humidity sensor has the advantages of small size,high temperature resistance,electromagnetic interference resistance,fast response speed,compact structure,simple manufacturing process and so on.Here,the research status and development trend of traditional optical fiber humidity sensors are first introduced.After that,the optical fiber evanescent field sensing technology and graphene oxide two-dimensional material are combined to design and produce a high-sensitivity evanescent field fiber optic humidity sensor based on micro capillary and graphene oxide(GO)film.The main research contents are as follows:This paper proposes a new evanescent field sensing structure based on the fused silica capillary and optical fiber.The sensor is made by welding a single-mode optical fiber on the end surface of the capillary by an optical fiber fusion splicer.The total length of the sensing area is only 1.5mm.When light enters the capillary wall from the introduced optical fiber,multiple modes can be stimulated in tubing wall and interfere with each other.The output signal of the sensing structure exhibits a sharp interference spectrum.As a new type of two-dimensional material,graphene oxide surface is modified with a large number of oxygen-containing functional groups and has excellent hydrophilicity,which makes it have unique advantages in humidity sensing.In this paper,graphene oxide material is used to modify the proposed optical fiber evanescent field sensor.First,we use sodium hydroxide to adjust the pH of the graphene oxide solution,and then apply 1,3,and 5 cycles of graphene oxide layer on the outer wall of the capillary by dip coating,respectively.Then,we conducted experimental and theoretical studies on the evanescent field excited by the interaction between graphene oxide and the capillary wall.The performance of the sensor was tested under the conditions of a temperature of 25 ° C and a relative humidity of 30% RH-70% RH.In this paper,the dip coating method is used to combine the multi-layer thin film technology with the optical fiber sensing technology.The sensing area uses micro capillary instead of traditional optical fiber.The obtained graphene oxide-based micro capillary fiber evanescent field sensor shows the humidity Sensitive response,its transmission spectrum has sharp peaks and troughs,and has a good signal-to-noise ratio as a sensor signal.And because the period of graphene oxide coating is controllable,the sensor has tunable humidity sensitivity.The humidity sensor has a compact structure,the preparation method used is simple,the preparation cost is low,and it is expected to be applied in an all-fiber network for environmental sensing and health monitoring.更多还原