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1、摘要光纤传感器因为具有抗电磁干扰、质量轻、结构紧凑等诸多优点，倍受学界与产业界重视，并已成为传感器领域的研究热点。本论文通过对光纤传感器的国内外研究现状的整理与总结，提出或改进了五种光纤干涉仪传感器，主要应用于折射率、温度、应变与液位测量，并使它们的灵敏度等性能指标有了显著提高。本篇论文的主要工作内容如下如下：（1）实验研究了飞秒激光微加工的特点，并利用飞秒激光对一种基于光子晶体光纤的马赫-泽德干涉仪进行微孔加工，然后进行折射率与应变测试，对比无孔干涉仪的相关灵敏度并分析原因。之后采用氢氟酸两次腐蚀微孔并进行折射率测试，对比每次腐蚀以后的折射率灵敏度并分析结果。最后在同尺寸的无孔式干涉仪进行双
2、微孔烧蚀加工并测试折射率灵敏度。（2）利用熔融-连接法制备两种迈克尔逊光纤干涉仪。一种是单锥式迈克尔逊光纤干涉仪，分析了不同熔接参数组合对单锥的信号损耗之间的影响，并应用该干涉仪进行了温度测试。另外制备了一种采用多模光纤的三明治式迈克尔逊光纤干涉仪，并将其用于测试液位深度。（3）利用CO2激光进行单点烧蚀的方法制备两种光纤干涉仪传感器，先制备出一种单锥式迈克尔逊光纤干涉仪，并用于测试液体折射率。之后加工出一种组合式马赫-泽德干涉仪，先后用于折射率与温度测试。本论文的主要创新点为：（1） 提出了一种利用飞秒激光加工的方法，改进原有的马赫-泽德干涉仪的性能参数，并应用于折射率检测。提出一种通过观测
3、干涉仪的传输谱的衰减峰大小来判定干涉仪是否可以停止加工的判断标准。研究发现在光子晶体光纤上烧蚀微孔可以提高原有干涉仪的折射率灵敏度，当加工出单孔时灵敏度是无孔时的2倍，而双孔时的灵敏度则是无孔时的5倍，孔的数量直接影响干涉仪的折射率灵敏度的提升。此外，氢氟酸腐蚀微孔的办法并不能提高干涉仪的折射率灵敏度。（2） 提出一种熔融-连接法制作单锥式光纤迈克尔逊干涉仪，并制备出最大衰减峰为16dB的干涉仪用于温度测试，适用于25-1000的测量范围，特别是在300-1000范围内时温度灵敏度为78pm/，高于其他类型的传感器，同时具有较好的热稳定性。针对干涉仪在低温与高温时所体现出的不同温度灵敏度，从理
4、论上进行分析与解释。（3） 提出一种基于单模-多模-单模（S-M-S）结构的光纤迈克尔逊干涉仪用于液位与折射率测试。由于多模光纤的长度直接决定干涉信号的衰减峰值，提出一种判定多模光纤长度的方法，通过比较引入的损耗信号强弱来决定最合适长度。并制备到最大衰减峰为13dB的干涉仪在多种不同折射率的液体中进行液位测试，测到液位灵敏度最大为-0.368nm/mm，折射率灵敏度为-41.69nm/RIU。（4） 提出一种利用CO2激光进行单点烧蚀法加工的单锥式迈克尔逊光纤干涉仪，端面镀膜后折射率灵敏度高达-197.3nm/RIU，远高于普通的长周期光栅传感器和普通锥结构的马赫-泽德光纤干涉仪。（5）采用同
5、样方法，改进一种双锥式马赫-泽德光纤干涉仪的加工方法，使其具有具有更高的折射率灵敏度。测得该干涉仪的折射率灵敏度为69.59nm/RIU，是双锥式干涉仪3倍多。后将其用于温度测量范围时，在500-800的温度范围内达到了0.1299 nm/的温度灵敏度，适用于高温区的温度测量。关键词 光纤传感器；飞秒激光微加工；熔融-连接；CO2激光；马赫-泽德干涉仪；迈克尔逊干涉仪；折射率传感器；温度传感器；光子晶体光纤 AbstractOptical fiber sensors have attracted increasing attention from the academia and indust
6、ry for their unique advantages such as immunity to electromagnetic interference, light weight and compact size. They are becoming the focus in sensor field. Previous work on the progress of fiber sensors at home and abroad is summarized in the thesis, and five fiber optic interferometric sensors are
7、 proposed, mainly employed for the refractive index, temperature, strain and liquid level sensing, respectively. Their sensitivity and other performance indexes are greatly improved for the proposed fiber sensors. The major contributions in this thesis are summarized as follows. (1) The characterist
8、ics of femtosecond laser micromachining are studied, a micro hole is machined on a PCF-based Mach-Zehnder interferometer using femtosecond laser, then the fabricated sensor is used in refractive index and strain sensing test. Then two experiments of micro-hole etching are done using hydrofluoric aci
9、d, the refractive index is tested after each etching and the data are recorded. The refractive index sensitivity in each etching step is contrasted and the result is analysed. Finally, a double micro-hole ablation process is operated on the PCF-based MZI with the same size, and the refractive index
10、sensitivity is tested. (2) A fusion-splicing method is applied for the preparation of two optic fiber Michelson interferometers. One of them is consisting of a single peanut taper and a free reflective fiber end, used for temperature sensing, besides that the effection of different combinations of w
11、elding parameters on signal loss introduced by single tapers is analyzed. The other one is a sandwich-type Michelson interferometer fabricated with the multi-mode fiber, then the liquid depth is tested with the fabricated sensor. (3) A single-spot irradiation method using the CO2 laser is applied fo
12、r the fabrication of two optic fiber interferometric sensors. The first device is a single taper Michelson interferometer, applied for refractive index sensing. The second device is a combined Mach - Zehnder interferometer, and it is used for the sensing of refractive index and temperature.The main
13、innovation of this paper is as follows: (1) A femtosecond laser processing methods is proposed to improve the original Mach - Zehnder interferometer performance index, and applied for refractive index sensing. A new criterion is proposed to determine whether the micromachining can be ceased throuth
14、the observation of attenuation peak in transmission spectrum of the interferometer. It is found that micro-hole ablation on the photonic crystal fiber can improve the refractive index sensitivity of the pervious interferometer in the study, i.e. the sensitivity of the device with single hole ablated
15、 is twice of the non-hole device, and the device with double hole ablated is five times larger than the non-hole device. The number of micro-holes can affect the rise of refractive index sensitivity directly. In addition, hydrofluoric acid etching can not increase the refractive index sensitivity of
16、 the interferometer. (2) A single peanut-type taper Michelson interferometer fabricated by fusion-splicing method is proposed, and the maximum attenuation of 16dB for the temperature sensing is achived. This new interferometer can be used to measure temperature ranging from 25 to 1000 , especially in the range of 300 -1000 , a temperature sensitivity of 78pm / can be achieved, higher than other types of sensors. Meanwhile it has good thermal st
