The Fundamental Limit of Fiber-Optic Sensors in the Infrasonic Region

次声波区域光纤传感器的基本极限

• 批准号: 1606836
• 负责人: Lingze Duan
• 金额: $ 34.03万
• 依托单位: University of Alabama in Huntsville
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1606836&HistoricalAwards=false
• 关键词: Fundamental; Limit; Fiber; Optic; Sensors

Abstract Title: The Fundamental Limit of Fiber-Optic Sensors in the Infrasonic RegionNontechnical: Fiber-optic sensors have been widely used in industry and research. However, one of their fundamental properties, the intrinsic limit of sensitivity, has not been fully understood. Specifically, at infrasonic frequencies (below 20 Hz), there has been no direct observation of the inherent noise in fiber-optic sensors, and the available theories remain inconclusive. The proposed project aims to address this problem by devising a set of experiments to probe the sensitivity-limiting noise in optical fibers and supporting the experimental study with advanced theoretical modeling. By uncovering the physics underlying the ultimate limit of sensor performance at low frequencies, the research will substantially deepen the understanding of infrasonic fiber-optic sensing, allowing future sensor designers to exploit the full potential of fiber-optic sensors at an unprecedented level of sensitivity. Moreover, the novel sensor designs used in the experiments will serve as blueprints for future ultra-sensitive distributed infrasound sensors, which are critical for monitoring mass-destruction weapons, earthquakes, volcanic eruptions, glacial motions, etc. The project will directly fund multiple students at both undergraduate and graduate levels and will generate capstone and summer research opportunities for college and high school students. It will also help create a new research thrust, precision fiber-optic sensing, at the University of Alabama in Huntsville, and improve the presence of NSF in the state of Alabama.Technical: The overarching goal of the planned research is to understand the physics that sets the ultimate limit of fiber sensor sensitivity at low frequencies. The investigation will primarily focus on direct measurement of the spontaneous thermal noise generated by optical fibers in the infrasonic region. A parallel effort will also be dedicated to the development of a three-dimensional visco-elastic model with concentric structures to describe the thermomechanical noise in optical fibers. To address the challenges facing the measurement of the minuscule thermal noise at infrasonic frequencies, a new sensor design based on a Mach-Zehnder-Fabry-Perot hybrid interferometer will be employed. Preliminary theoretical analysis has shown that such a scheme is able to raise the sensor sensitivity by a factor of 104, hence extending the thermal noise-dominated spectral region to well below 1 Hz. The scientific merit of the proposed research rests upon its primary goal toward uncovering the fundamental physical law of fiber thermal noise. The mystery surrounding the 1/f behavior of fiber thermal noise has puzzled researchers for two decades. There is an urgent need within the fiber-optic sensor community for a thorough investigation specifically targeting the low-frequency characteristics of thermal noise. By leveraging new sensing concepts such as hybrid interferometers, the proposed work will completely transform optical sensing for low-frequency signals and open up a new paradigm of infrasonic technologies.

摘要题目：光纤传感器在次声领域的基本限制非技术：光纤传感器在工业和研究中得到了广泛的应用。然而，它们的一个基本性质，即灵敏度的内在极限，还没有被完全理解。具体来说，在次声频率（低于20赫兹）下，没有直接观察到光纤传感器的固有噪声，现有的理论仍然没有定论。该项目旨在通过设计一套实验来探测光纤中的灵敏度限制噪声，并通过先进的理论建模来支持实验研究，从而解决这一问题。通过揭示低频下传感器性能极限的物理基础，该研究将大大加深对次声光纤传感的理解，使未来的传感器设计师能够在前所未有的灵敏度水平上开发光纤传感器的全部潜力。此外，实验中使用的新型传感器设计将为未来的超灵敏分布式次声传感器提供蓝图，这些传感器对于监测大规模杀伤性武器、地震、火山爆发、冰川运动等至关重要。该项目将直接资助多名本科生和研究生，并将为大学和高中学生提供顶点和暑期研究机会。它还将有助于在亨茨维尔的阿拉巴马大学创建一个新的研究重点——精确光纤传感，并提高美国国家科学基金会在阿拉巴马州的存在。技术：计划研究的首要目标是了解在低频下光纤传感器灵敏度的最终限制的物理原理。研究将主要集中在直接测量由光纤产生的自发热噪声在次声区域。同时，还将致力于开发具有同心结构的三维粘弹性模型，以描述光纤中的热机械噪声。为了解决在次声频率下微小热噪声测量所面临的挑战，将采用一种基于Mach-Zehnder-Fabry-Perot混合干涉仪的新型传感器设计。初步的理论分析表明，这种方案能够将传感器灵敏度提高104倍，从而将热噪声主导的光谱区域扩展到远低于1hz。所提出的研究的科学价值在于其主要目标是揭示光纤热噪声的基本物理规律。围绕纤维热噪声的1/f行为的谜团已经困扰了研究人员二十年。在光纤传感器领域，迫切需要对热噪声的低频特性进行深入的研究。通过利用混合干涉仪等新的传感概念，提出的工作将彻底改变低频信号的光学传感，并开辟次声技术的新范式。