【作者】 李平；

【导师】 张新陆；

【作者基本信息】 哈尔滨工程大学 ， 光学工程， 2021， 博士

【摘要】 随着科技进步,物联网高速发展,从生产加工到物流汇通,从精细控制到全球物联,从医疗检测到国家安防,对信息获取的需求正向多元化发展。光纤传感器具有灵敏度高、响应速度快,稳定性好、能适应恶劣环境等优点,在工程领域已经得到了广泛的应用。传统光纤传感器已经无法满足低串扰、高集成和多功能的需求,提出新型光纤传感器件成为的应用研究的热点。本文开展的工作是利用特种光纤在模式、结构等方面的多样性,提出了多种功能各异的光纤传感器,从理论和实验的角度对其传感特性进行了深入研究,并探索了纤内集成传感。本论文的主要工作包括:1、研究基于偏芯少模光纤的芯模-芯模型Mach-Zehnder干涉仪的传感特性。利用光纤错位熔接技术同时激发少模光纤纤芯中的LP₀₁与LP₁₁模式,并利用光纤腐蚀技术减弱了包层模式的激发,实现纤芯内LP₀₁模与LP₁₁模的模式干涉。与同种光纤构建的芯模-包层模干涉仪相比,芯模-芯模型双模干涉仪具有更高的折射率灵敏度和较低的温度灵敏度。当折射率在1.335～1.400范围内时,该干涉仪的平均折射率灵敏度为1300.4nm/RIU,在环境折射率约为1.400时可达2565.2 nm/RIU。当温度在20°C～200°C范围内时,温度灵敏度仅为-9.6 pm/°C。该芯模-芯模型Mach-Zehnder干涉仪可以实现低温度串扰的高灵敏度折射率传感器。2、研究基于少模孔助偏芯光纤的Mach-Zehnder干涉仪的传感特性。仿真分析了孔助偏芯光纤空气孔中填充和未填充液体两种情况下的模式激发特性,确定了两种情况下构成Mach-Zehnder干涉仪的最佳耦合错位熔接距离,并对其折射率传感及温度传感特性进行了仿真分析和实验验证。由于空气孔的存在,孔助偏芯光纤少模干涉仪可用作低温度串扰的光纤微流通道折射率传感器。提出了基于孔助偏芯光纤的弯曲补偿型长周期光纤光栅。利用光纤错位熔接技术使孔助偏芯光纤纤芯在光纤径向反方位熔接,在熔接点两侧对称地写入长周期光栅。由于径向弯曲熔接点两侧的光栅具有完全相反的弯曲响应,因此具有抗弯效应,弯曲灵敏度仅为0.47 nm/m^-1,在温度30°C～210°C,该结构对温度响应灵敏度约为55 pm/°C。基于少模孔助偏芯光纤的Mach-Zehnder干涉仪折射率传感器可作为一种抗弯型温度传感器。3、研究基于线性阵列5芯光纤的Mach-Zehnder干涉仪传感特性。对线性阵列5芯光纤超模的模间干涉进行了研究。芯模间的干涉对轴向应变和曲率变化不敏感,芯模和包层模间的干涉对垂直于纤芯排列方向的应变和弯曲非常敏感,应变和弯曲灵敏度分别为-0.8 pm/με和10.37 nm/m^-1。所提出的Mach-Zehnder干涉仪能够利用不同的模式干涉实现对不同物理参量的传感。4、研究基于双周期线性阵列6芯光纤的布拉格光栅的传感特性。讨论了异质双周期线性阵列6芯光纤的超模特性,两组不同尺寸的纤芯形成两个独立的超模群,并在6个纤芯上分别刻写了布拉格光栅。每个纤芯内布拉格光栅的温度灵敏度约为10 pm/°C,轴向应变灵敏度约为1 pm/με。所提出的异质双周期线性阵列6芯光纤可以将不同谐振波长的布拉格光栅集成到同一平面。更多还原

【Abstract】 With the progress of science and technology and the rapid development of the Internet of Things,the demand for information acquisition is developing in a multidisciplinary way from production and processing to logistics convergence,from subtle control to the global Internet of things,from medical detection to national security.Fiber optic sensors have been widely used in engineering because of their advantages such as high sensitivity,fast response speed,excellent stability and adaptability to harsh environment.Traditional optical fiber sensors can no longer meet the requirements such as low crosstalk,high integration and multifunctionality,therefore the new type of optical fiber sensor is a key problem to be solved urgently.The work carried out in this dissertation is to design a variety of optical fiber sensors with different functions by use of the diversity of modes and structures in special optical fibers and comprehensively investigate the sensing characteristics based on theory and experiment.The properties of the sensor integrated inside the fiber have been explored.This work is of great significance to promote the development of optical fiber sensing technology.The main work of this dissertation includes:1.A Mach-Zehnder interferometer in the eccentric core few mode fiber has been propose using the core mode-core modes interaction.The LP₀₁ and LP₁₁ modes in the fiber core are simultaneously excited by the fiber fusion technology with displacement,and the cladding mode excitation is reduced by the fiber etched technology,thus the mode interference between the LP₀₁ and LP₁₁ modes in the fiber core has been realized.Compared with the core cladding mode interferometer constructed by the same fiber,the core mode-core mode dual-mode interferometer has higher refractive index sensitivity and lower temperature sensitivity.When the refractive index is 1.335～1.400,the average refractive index sensitivity of the interferometer is 1300.4 nm/RIU,and reaches the maximum value of up to 2565.2 nm/RIU when the environmental refractive index is about 1.400.At 20°C～200°C,the temperature sensitivity is only-9.6 pm/°C.The core-core mode Mach-Zehnder interferometer can be used as a high sensitivity refractive index sensor with low temperature crosstalk.2.A Mach-Zehnder interferometer has been designed based on few mode hole assisted eccentric fiber.The mode excitation characteristics of the fiber have been simulated and analyzed when the air hole is filled with and without liquid.The displacement distance of Mach-Zehnder interferometer has been determined when the optimal coupling occurs during the fiber splicing.The refractive index and temperature sensing characteristics have been simulated and verified by experiments.Because of the existence of the air hole,the hole assisted eccentric fiber few mode interferometer can be used as micro-channel refractive index sensor with low temperature crosstalk.A long period fiber grating with bending compensation has been proposed in hole assisted eccentric fiber.By means of optical fiber fusion technology with displacement,the core of hole assisted eccentric fiber is fused in the opposite radial direction and the long period grating is written symmetrically on both sides of the fusion junction.Since the gratings on both sides of the fusion junction have completely opposite bending responses during the radial bending,the fiber has an anti-bending effect.The bending sensitivity is only0.47 nm/m^-1.At the temperature of 30°C～210°C,the sensitivity of the structure to temperature is about 55 pm/°C.The Mach-Zehnder interferometer refractive index sensor based on the few mode hole assisted eccentric fiber can be used as an anti-bending temperature sensor.3.A Mach-Zehnder interferometer has been proposed in linear array 5-core fiber.The modal interference of the super-mode has been studied in a linear array 5-core fiber.The interference between the core mode and core mode is insensitive to the changes of axial strain and curvature,while the interference between the core mode and cladding mode is very sensitive to strain and bending perpendicular to the core alignment direction.The strain and bending sensitivities are-0.8 pm/μεand 10.37 nm/m^-1,respectively.The proposed Mach-Zehnder interferometer can realize the sensing responses of different physical parameters by using different mode interferences.4.A fiber Bragg grating（FBG）has been proposed in heterogeneous double period linear array 6-core fiber.The super-mode characteristics of heterogeneous double period linear array6-core fiber have been discussed.Two independent super-mode groups are formed in two core groups with different sizes.In addition,fiber Bragg gratings have been written upon the six cores,respectively.The temperature sensitivity of fiber Bragg grating within each core is approximate 10 pm/°C and the axial strain sensitivity is approximate 1 pm/με.The proposed Bragg grating in heterogeneous double period linear array 6-core fiber can be integrated in the same plane,working at different resonant wavelengths,and it has potential applications in the fields of spatial division multiplexing,lasers and sensors.更多还原