【作者】 吴越；

【导师】 简水生；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2018， 博士

【摘要】 光纤传感网络在军事安防、生物传感、环境检测、城市建设等方面发挥着重要的作用,光纤激光器和光纤传感器作为光纤传感网络中的关键器件,受到了广泛的关注和研究。光纤激光器具有较高的输出功率和光信噪比等特点,因此,光纤激光器在远距离的光纤传感网络中具有较大优势;多波长光纤激光器可以同时输出多个波长激光,具有成本低、结构紧凑等优点,在远距离、多点的传感网络中占据着重要作用,同时,多波长光纤激光器也是高速光通信网络中多信道通信的理想光源。光纤传感器具有结构紧凑、抗电磁干扰、成本低、敏感度高、耐腐蚀等优点,其在小型化、多功能化的传感网络中承担着重要的作用。本文对光纤传感网络中的多波长光纤激光器和基于干涉原理的光纤传感器进行了研究。本论文的研究成果如下:1.在前人工作的基础上,基于采样光纤光栅滤波器,并结合液氮冷却技术,利用保偏掺铒光纤和普通掺铒光纤实验了 4种多波长光纤激光器,并分别对其输出特性和偏振特性进行了分析。将多波长光纤激光器作为传感系统的光源,结合波分复用器,并利用光纤端面的反射特性,制作了折射率传感器。根据实验结果得到,该传感系统的折射率敏感度为132.52dB/RIU。同时,该传感系统具有多点折射率测量的潜能。2.以无芯光纤、空芯光纤、弯曲单模光纤为基础,提出并制作了三种模式干涉型光纤传感器。在不同折射率溶液、无芯光纤半径、无芯光纤长度下,分析了溶液的液位对无芯光纤模式干涉仪传输谱的影响,以无芯光纤模式干涉结构为基础,制作了高气压敏感度的传感器,通过实验与理论研究了不同空气腔的腔长与传感器气压敏感度之间的关系,实验获得该传感器最大的气压敏感度为266.6 nm/Mpa。制作了无芯光纤-空芯光纤-无芯光纤结构的紧凑型传感器,两段无芯光纤分别熔接在空芯光纤的两端,作为光束的合束器和分束器。在实验中分析不同长度的空芯光纤对模式干涉仪传输谱的影响,并对传感器的应力响应特性和温度响应特性进行了研究。制作了弯曲单模光纤的高拉力敏感度传感器,该模式干涉结构由不带涂覆的单模光纤弯曲而成。通过实验分析了不同弯曲直径对模式干涉仪传输谱的影响,实验获得该传感器的最大拉力敏感度为24.9 pm/μN。3.提出了基于非对称双芯光纤和多模光纤的传感器,从实验和理论两个方面分析了双芯光纤的非耦合特性。多模光纤焊接在双芯光纤的两端,作为光束的合束器和分束器,且该结构传输谱的消光比约为15 dB。在实验中将该传感器应用于曲率和应力的测量,通过测量得到该传感器的最大曲率敏感度为103.35 nm/m-1,最大应力敏感度为-4.01pm/με。4.提出了非对称的法布里珀罗干涉仪,实现了对温度和曲率的同时测量。该法布里珀罗干涉仪由弱反射光纤光栅和无芯光纤组成。通过理论和实验两个方面对干涉仪的曲率响应特性和温度响应特性进行了分析。结果显示,温度的变化会影响干涉仪的峰值波长漂移,不会对消光比产生影响;而曲率的变化会引起干涉仪消光比的变化,不会使峰值波长发生漂移。传感器的温度敏感度10.2 pm/℃,在曲率为0.8844 m-1-1.0995 m-1的范围内,测量的曲率敏感度为9.57 dB/m-1。更多还原

【Abstract】 Optical fiber sensor network plays an important role in military security,bio-sensing,environmental detection,and urban construction.Fiber laser and fiber-optic sensor are key components in optical fiber sensor network,which have received extensive attention and research.Fiber lasers have features such as higher output power and optical signal to noise ratio.Therefore,fiber lasers have great advantages in long-distance fiber sensor network.Multi-wavelength fiber laser can output multiple wavelength lasers at the same time,which has the advantages of low cost and compact structure,and it occupies an important role in long-distance,multi-point sensor network.At the same time,multi-wavelength fiber laser is ideal light source for multi-channel communication in high-speed optical communication network.The optical fiber sensor has the advantages of compact structure,anti-electromagnetic interference,low cost,high sensitivity,corrosion resistance,etc.It plays an important role in a miniaturized,Multi-functional sensor network.In this paper,we study multi-wavelength fiber laser and optical fiber sensors based on the principle of interference in fiber-optic sensor network.The main research results are listed as follows:1.On the basis of previous work,based on the sampling fiber grating filter and liquid nitrogen cooling technology,four kinds of multi-wavelength fiber lasers are tested by using polarization-maintaining erbium-doped fiber and common erbium-doped fiber,and their output characteristics were respectively and polarization characteristics are analyzed.A multi-wavelength fiber laser is used as light source of the sensing system,combined with a wavelength division multiplexer,and a refractive index sensor is fabricated by utilizing the reflection characteristics of the end face of the fiber.According to the experimental results,the sensing system has refractive index sensitivity of 132.52 dB/RIU.At the same time,the sensing system has the potential for multi-point refractive index measurement.2.Based on no-core fiber,hollow-core fiber and bent single mode fiber,three mode interference fiber sensors are proposed and fabricated.Under different refractive index solutions,no-core fiber radius and no-core fiber length,the influence of solution liquid level on the transmission spectrum of no-core fiber mode interferometer are analyzed.Based on the no-core fiber mode interference structure,high air pressure sensitivity is fabricated.The relationship between the cavity length of different air cavities and the sensitivity of the sensor has been studied experimentally and theoretically.The maximum pressure sensitivity of the sensor is 266.6 nm/Mpa.A compact sensor with a no-core fiber hollow-core fiber no-core fiber structure is fabricated.Two segment of no-core fiber are respectively fused at both ends of the hollow-core fiber to serve as a beam combiner and beam splitter.In the experiment,the influence of different lengths of hollow-core fiber on the transmission spectrum of the mode interferometer is analyzed,and the stress response characteristics and temperature response characteristics of the sensor are studied.A high force sensitivity sensor of a bent single mode fiber is fabricated,and the mode interference structure is formed by bending a single-mode fiber with coating stripped.The influence of different bending diameters on the transmission spectrum of the mode interferometer is analyzed by experiments.The maximum force sensitivity of the sensor is 24.9 pm/pN.3.A fiber senor based on asymmetrical twin core fiber and multimode fiber is proposed.From both experiment and coupled-mode theory,the uncoupled characteristics of twin core fiber is analyzed.Two segments of multimode fiber used as beam splitter and combiner are embedded on the two ends of the twin core fiber,and the extinction ratio of the comb transmission spectrum of the fiber sensor is about 15 dB.In the experiment,the fiber sensor is applied to the measurement of curvature and strain.The experimental results show that the maximum curvature sensitivity of this sensor is 103.35 nm/m-1 and the maximum strain sensitivity is-4.01pm/με.4.An asymmetric Fabry-Perot interferometer for simultaneous measurements of temperature and curvature is proposed.The Fabry-Perot interferometer is comprised of a low reflective fiber Bragg grating with narrow bandwidth and a no-core fiber with broadband Fresnel reflection.From both experiment and theory,the curvature response and temperature response characteristics of the interferometer are analyzed.The results show that the temperature variation will affect the peak wavelength of the interferometer shift and has no influence on the extinction ratio.While the change of curvature will cause the extinction ratio of the interferometer change and has no effect on the peak wavelength.According to the measurement results,the temperature sensitivity of the sensor is 10.2 pm/℃,and the curvature sensitivity is 9.57 dB/m-1 in the range of 0.8844 m’1 to 1.0995 m-1.更多还原