【作者】 周昌学；

【导师】 饶云江；

【作者基本信息】 重庆大学 ， 光学工程， 2006， 硕士

【摘要】 光纤传感技术由于具有抗干扰能力强、本质安全、可测量量多、测量动态范围大、可远程监测等优点,在光纤技术发展起来后就立即引起了众多研究人员的兴趣。光纤Fabry-Perot(F-P)传感器是技术最为成熟、应用最为广泛的光纤传感器之一。论文首先对光纤Fabry-Perot传感器的原理、结构作了一些简单的介绍,然后详细分析了光纤Fabry-Perot传感器复用技术的发展现状,发现现有的光纤Fabry-Perot传感器复用效率比较低,复用系统的结构也比较复杂,实用价值不大,因此探索更先进、更简单实用,更经济的复用方法对推动光纤Fabry-Perot传感器的研究及应用具有十分重要的意义。首先提出了光纤Fabry-Perot传感器的波分复用方法,并讨论了光纤EFPI传感器与光纤Fizeau传感器在复用能力上的差异;建立了光纤EFPI传感器的粗波分复用系统,并进行应变测量实验,实验结果表明该传感器复用系统性能优良,应变测量精度高,达到±2.5με。对光纤Fizeau传感器空间频分复用原理和解调算法进行分析,并根据实际需要选择傅里叶解调算法作为最合适的解调方法;组合光纤Fabry-Perot传感器波分复用方法与光纤Fizeau传感器空间频分复用(SFDM)方法,提出了光纤Fizeau传感器频分波分(SFDM/WDM)复用方法,该方法可复用传感器数量是波分与空间频分复用数量的乘积,其复用潜力巨大,理论上可以复用近一百的传感器;建立了基于SFDM/CWDM复用方法的应变测量系统;应变实验发现腔长差较小的两光纤Fizeau传感器在SFDM复用系统中会出现较大的串扰,对串扰产生的原因进行了详细的分析,提出了解决串扰的加窗技术方法和最小方均值方法;对加窗技术方法,通过数值模拟与实验选择了最为合适的窗函数;对最小方均值方法,使用分布搜索法,提高了计算效率;应变测量实验表明其应变测量精度较高;系统结构简单,复用潜力大,是一种非常好的复用方法;最后还对光纤Fizeau传感器的温度系数与其激光封装技术进行了探讨。为了更进一步的提高光纤F-P传感器的SFDM/WDM复用能力,提出了用IFPI传感器代替光纤Fizeau传感器来进行应变测量的思想,并通过分析选择啁啾光栅F-P传感器作为适合复用的IFPI传感器结构。从光纤光栅的传输矩阵理论出发,通过均匀分段法对啁啾光栅进行了数值模拟,然后根据实验需求优化了啁啾光纤光栅的设计参数,并由此设计出合适的光纤光栅F-P传感器;根据传感器的设计得出了啁啾光栅传感器的反射谱,然后根据应变下光纤的拉长及光纤材料的弹光更多还原

【Abstract】 As an important member of optical fiber sensors family, fiber Fabry-Perot interferometric sensors are being intensively studied as they have many advantages over conventional electrical sensors, such as immunity to electromagnetic interference, capability of responding to a wide variety of measurands, high resolution, high accuracy, small size, etc. Fabry-Perot sensors have been commercialized and widely used in health monitoring for composite materials, large civil engineering infrastructures (e.g. bridges and dams), space aircrafts, airplanes, oil fields, engines, etc., which would lead to the realization of so-called smart materials and structures. However, Fabry-Perot sensors have one intrinsic disadvantage i.e. they are difficult to multiplex. As the result, the cost of the sensor system with a large number of Fabry-Perot sensors is normally high. Hence, we would find some ways to overcome the problem.First,a method based on the coarse wavelength-division-multiplexing technology (CWDM) is proposed to overcome the intrinsic disadvantage of Fabry-Perot sensors. Each Fabry-Perot sensor will occupy a wavelength window predetermined by a CWDM device. This system improves the multiplexing capability of Fabry-Perot sensors by a factor of four. A strain measurement accuracy of better than±2.5μεhas been achieved, which can meet the practical requirement well.A novel method based on the combination of coarse wavelength division multiplexing (CWDM) and spatial frequency division multiplexing (SFDM) is proposed to overcome the disadvantage of Fabry-Perot interferometric sensors. In this work, more than 10 Fizeau strain sensors can be multiplexed using SFDM in each wavelength channel predetermined by CWDM. This method can multiplex a large number of sensors of up to 100 in principle and hence can reduce the cost of the whole sensor system greatly. Also, this hybrid method can take the advantages of both SFDM and CWDM when applied to the multiplexing of a large number of sensors, i.e. excellent multiplexing capability when using SFDM, and good efficiency in using every part of the optical power of the broadband source with CWDM.In order to enhance the number of multiplexed F-P sensors to realize strain monitoring of large engineering structures, intrinsic fiber Fabry-Perot interferometric sensors (IFPIs) are taken into account in this work. The cavity length of an IFPI can be as long as tens of mm hence the sensor number that can be multiplexed is much more更多还原