Recent developments of optical fiber sensors for automotive use

Optical fiber sensing technologies are expected to apply for many future electronic control systems in automobiles, because of their inherent outstanding features, such as high noise immunity, high heat resistance, and flexible light propagation paths which can be applied to measure the movements and directions of the mobiles. In this paper, two typical applications of fiber sensing technologies in automobiles are described in detail. The combustion flame detector is one of the typical applications of a fiber spectroscopic technology which utilizes the feature of high noise and heat resistibility and remote sensibility. Measurement of engine combustion conditions, such as the detonation, the combustion initiation, and the air-fuel ratio, have been demonstrated in an experimental fiber sensing method. Fiber interferometers, such as a fiber gyroscope, have great possibilities in future mobile applications because they are applicable to many kinds of measurements for movements and physical variables. An optical fiber gyroscope utilizing the single polarized optical fiber and other optical devices has been developed. Quite an accurate measurement of vehicle position was displayed on a prototype navigation system which installed the fiber gyroscope as a rotational speed sensor.     

基于时分复用技术的三轴光纤陀螺光路噪声及抑制技术研究

光纤陀螺小型化是光纤陀螺发展的一个重要方向,提出了一种基于时分复用技术的三轴光纤陀螺光路结构,通过复用一个光源和一个探测器大大减少了器件数量,有效地降低了成本,减小了体积。针对三轴光纤陀螺单信道多信号传感理论进行分析,给出了一种有效的信号提取方案,最后对光路串扰噪声进行了研究,提出一种噪声抑制技术并进行了实验验证。测试结果表明,噪声抑制技术效果良好,陀螺精度满足工程应用要求。     

分立式与分布式光纤传感关键技术研究进展

光纤传感技术已广泛应用于航空航天、石油化工、电子电力、土木工程、生物医药等领域,其技术形式主要体现为分立式和分布式.分立式光纤传感技术利用光纤敏感器件作为传感器来感知被测参量的变化,光纤作为光信号的传输通道连接光纤传感器及后端的解调装置;分布式光纤传感系统基于光纤瑞利散射、拉曼散射或布里渊散射等光学效应,利用光纤本身作为传感器,可对沿途的光信号进行大范围、长距离传感.本文介绍了分立式与分布式光纤传感中主要关键技术的研究进展,并对未来的研究和发展方向进行了探讨.     

谐振式光纤陀螺偏振噪声分析

谐振式光纤陀螺（R～FOG）是第二代光纤陀螺,其性能受各种噪声因素的影响。为提高谐振式光纤陀螺的性能,对谐振式光纤陀螺的瑞利背向散射、克尔效应、磁光法拉第效应和偏振态耦合等各种噪声进行了分析,并提出了对偏振态耦合噪声的解决方法。在此基础上,得到保偏光纤环旋转90°对接的谐振腔优化结构。该结构可以有效减小谐振腔的偏振噪声和磁光法拉第噪声,且可改善陀螺系统的温度特性。     

相位敏感型光时域反射传感系统光学背景噪声的产生机理及其抑制方法

相位敏感型光时域反射(Φ-OTDR)传感系统具有响应速度快、灵敏度高等优点,能够实现对微弱扰动的分布式检测,在重大设施的入侵警戒、大型工程结构的健康监测等领域具有广阔应用前景.然而,与传统的OTDR传感系统不同,Φ-OTDR系统中存在着激光器中心频率漂移、偏振相关的噪声、光纤应变与干涉强度非线性对应关系引起的测量失真等光学背景噪声,对有效信号的提取形成了不可忽视的干扰,从而限制了Φ-OTDR传感系统在实际应用环境下的传感性能.本文对这些光学背景噪声的产生机理进行了深入分析,并提出了相应的噪声抑制方法.实验结果表明,本文提出的方法可以有效抑制Φ-OTDR传感系统中的光学背景噪声,并显著提高传感系统性能.     

基于布里渊散射的分布式光纤传感技术

基于布里渊散射的分布式光纤传感技术是目前国内外研究的热点。其中基于时域定位的布里渊分布式光纤传感技术主要分为布里渊光时域反射和布里渊光时域分析两种。国内对基于布里渊光时域反射技术的分布式光纤传感技术的研究报道比较多。介绍了基于布里渊光时域分析技术的分布式光纤传感技术的研究现状,并对基于时域定位的两种传感技术进行了分析对比。总结了布里渊散射分布式光纤传感技术实用化存在的问题及可能的解决方法,指出了该传感技术进一步的发展方向。     

Drive to miniaturization: integrated optical networks on mobile platforms

With rapid growth of the Internet, bandwidth demand for data traffic is continuing to explode. In addition, emerging and future applications are becoming more and more network centric. With the proliferation of data communication platforms and data-intensive applications (e.g. cloud computing), high-bandwidth materials such as video clips dominating the Internet, and social networking tools, a networking technology is very desirable which can scale the Internet’s capability (particularly its bandwidth) by two to three orders of magnitude. As the limits of Moore’s law are approached, optical mesh networks based on wavelength-division multiplexing (WDM) have the ability to satisfy the large- and scalable-bandwidth requirements of our future backbone telecommunication networks. In addition, this trend is also affecting other special-purpose systems in applications such as mobile platforms, automobiles, aircraft, ships, tanks, and micro unmanned air vehicles (UAVs) which are becoming independent systems roaming the sky while sensing data, processing, making decisions, and even communicating and networking with other heterogeneous systems. Recently, WDM optical technologies have seen advances in its transmission speeds, switching technologies, routing protocols, and control systems. Such advances have made WDM optical technology an appealing choice for the design of future Internet architectures. Along these lines, scientists across the entire spectrum of the network architectures from physical layer to applications have been working on developing devices and communication protocols which can take full advantage of the rapid advances in WDM technology. Nevertheless, the focus has always been on large-scale telecommunication networks that span hundreds and even thousands of miles. Given these advances, we investigate the vision and applicability of integrating the traditionally large-scale WDM optical networks into miniaturized mobile platforms such as UAVs. We explain the benefits of WDM optical technology for these applications. We also describe some of the limitations of WDM optical networks as the size of a vehicle gets smaller, such as in micro-UAVs, and study the miniaturization and communication system limitations in such environments.     

Photonic sensing technology is opening new frontiers in biophotonics

In advanced sensing photonics it is of great importance to explore the detection limits of extremely weak optical signals and imaging using state-of-the art technology. In this paper we describe recent progress in photonic sensing technology achieved in practice in the standard quantum limit of optical detection imposed by the signal-limited shot noise, which can be realized by both the optical heterodyne detection and photon counting techniques. Then, with particular attention on imaging of ultraweak photonic signals by these techniques, their applications in developing new frontiers in the field of biophotonics such as laser computed tomography, and the imaging and characterization of ultraweak biophoton emission phenomena are described and discussed as one of the typical examples of future trends in this field.     

基于光纤微结构加工和敏感材料物理融合的光纤传感技术

将功能敏感材料与光纤在物理层面进行有机融合,充分发挥光纤传感器在结构集成、材料集成等方面的优势,将有望发展新型的光纤传感器件和系统.本文综述了飞秒激光光纤微加工技术分别在标准的单模光纤和光纤光栅上制备微结构,再结合敏感材料制备技术,实现在物理层面上光纤传感器材料和结构的集成和融合,探索实现新型高性能的光纤传感新技术.     

Coherent fiber supercontinuum for biophotonics

Biophotonics and nonlinear fiber optics have traditionally been two independent fields. Since the discovery of fiber‐based supercontinuum generation in 1999, biophotonics applications employing incoherent light have experienced a large impact from nonlinear fiber optics, primarily because of the access to a wide range of wavelengths and a uniform spatial profile afforded by fiber supercontinuum. However, biophotonics applications employing coherent light have not benefited from the most well‐known techniques of supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, and inadequate portability. Fortunately, a few key techniques involving nonlinear fiber optics and femtosecond laser development have emerged to overcome these critical limitations. Despite their relative independence, these techniques are the focus of this review, because they can be integrated into a low‐cost portable biophotonics source platform. This platform can be shared across many different areas of research in biophotonics, enabling new applications such as point‐of‐care coherent optical biomedical imaging.     

长周期光栅生物传感器研究进展

长周期光纤光栅是对周围环境比较敏感的一种无源光学器件,由于其具有无后向反射、对折射率灵敏度高、体积小、易于集成化、不受电磁干扰、耐酸碱腐蚀、不需要参比电极等诸多特点,在折射率传感领域备受关注。自从2000年Bentley研究组第一次将长周期光纤光栅用于抗原的检测以来,经过十余年的发展,长周期光栅在生物物质的检测方面取得了很大的进展,已被用于抗原抗体、细菌病毒、蛋白质、DNA、酶及核酸等诸多生物物质的检测。本文对长周期光纤光栅近年来在生物传感领域的研究进展和应用进行了总结和评述,并对长周期光纤光栅在生物物质检测方面的未来发展趋势做了展望。     

Erbium‐doped integrated waveguide amplifiers and lasers

Erbium‐doped fiber devices have been extraordinarily successful due to their broad optical gain around 1.5–1.6 µm. Er‐doped fiber amplifiers enable efficient, stable amplification of high‐speed, wavelength‐division‐multiplexed signals, thus continue to dominate as part of the backbone of longhaul telecommunications networks. At the same time, Er‐doped fiber lasers see many applications in telecommunications as well as in biomedical and sensing environments. Over the last 20 years significant efforts have been made to bring these advantages to the chip level. Device integration decreases the overall size and cost and potentially allows for the combination of many functions on a single tiny chip. Besides technological issues connected to the shorter device lengths and correspondingly higher Er concentrations required for high gain, the choice of appropriate host material as well as many design issues come into play in such devices. In this contribution the important developments in the field of Er‐doped integrated waveguide amplifiers and lasers are reviewed and current and future potential applications are explored. The vision of integrating such Er‐doped gain devices with other, passive materials platforms, such as silicon photonics, is discussed.     

Sensitive interferometric detection of ultrasound for minimally invasive clinical imaging applications

Miniaturized optical detectors of ultrasound represent a promising alternative to piezoelectric technology and may enable new minimally invasive clinical applications, particularly in the field of optoacoustic imaging. However, the use of such detectors has so far been limited to controlled lab environments, and has not been demonstrated in the presence of mechanical disturbances, common in clinical imaging scenarios. Additionally, detection sensitivity has been inherently limited by laser noise, which hindered the use of sensing elements such as optical fibers, which exhibit a weak response to ultrasound. In this work, coherence‐restored pulse interferometry (CRPI) is introduced – a new paradigm for interferometric sensing in which shot‐noise limited sensitivity may be achieved alongside robust operation. CRPI is implemented with a fiber‐based resonator, demonstrating over an order of magnitude higher sensitivity than that of conventional 15 MHz intravascular ultrasound probes. The performance of the optical detector is showcased in a miniaturized all‐optical optoacoustic imaging catheter.     

基于光纤的光学频率传递研究

随着光钟研究的发展, 光钟的稳定度和不确定度均达到10^-18量级. 通过光纤可以实现光钟频率信号的高精度传输, 有望用于未来“秒”定义的复现. 演示了百公里级实验室光纤上的光学频率传递. 对于在实验室70 km光纤盘上实现的光频传递, 光纤相位噪声抑制在1-250 Hz傅里叶频率范围内均接近于光纤延时极限, 对应传输稳定度(Allan偏差)为秒级稳定度1.2×10^-15, 10000 s稳定度为1.4×10^-18. 实验室100 km光纤的光频传递秒级稳定度也达到了5×10^-15. 提出了光纤噪声用户端补偿的方案, 可以简化星形传递网络中心站的复杂度. 在25 km光纤上演示了该传递方案, 实现的传输稳定度接近传统前置补偿传递方案.     

L波段高掺铒光纤超荧光光源

采用半导体激光二极管泵浦12cm长高掺铒光纤,在双程前向装置中,获得了10.8mW最大超荧光输出功率,斜率效率10.6%,在1553.1~1588.6nm接近36nm的范围内,功率抖动小于0.2dBm。作为比较,在相同实验条件下泵浦10cm长的高掺铒光纤,结果显示输出光谱带宽明显下降,C波段的放大自发辐射远大于L波段的,由此也证明了L波段的放大自发辐射是由C波段的放大自发辐射泵浦产生的。     

Fiber optic sensor interface standardization

The need for a new avionic interconnection scheme that can provide superior performance, installability and maintainability as compared with copper has become evident. Fiber optics, which has been proposed for this role, is expected to improve environmental immunity, decrease system weight, and increase bandwidth. It has also been suggested that sensors based on fiber optics can offer significant advantages in aerospace applications. Realizing these advantages is a difficult challenge because mature sensing technologies have done a good job at reasonable cost. Furthermore, it has been demonstrated that a wide variety of aircraft electrical sensors can be addressed by a few standard interfaces. Therefore, future fiber optic sensor suites will also need to be interrogated through only a few standard interfaces, and standardization of the fiber optic sensor interface will be a primary issue in furthering fiber optic sensing technology for aerospace applications. This paper discusses the fiber optic sensor standardization process underway in the Avionic Systems Division of the Society of Automotive Engineers.     

陀螺惯性制导及其军事应用

简要介绍机械惯性陀螺、环形激光陀螺、光纤陀螺、半球谐振陀螺、石英音叉陀螺的基本工作原理及其军事应用,并预测了陀螺惯性制导的发展趋势。     

光纤激光模场及表征技术进展

在光纤通信、光纤激光器和光纤传感等领域的实际应用中,需要重点关注光纤中的模式问题。模分复用是提高光通信信息容量的有效方法,模间干涉是大多数光纤传感的基本方法,高功率光纤激光的光束质量控制的关键技术之一就是模式控制,因此,对光纤模式理论、模式产生及转换、模式表征技术开展研究具有重要的研究意义和实际应用价值。论文讨论了光纤的模式及光束质量,分析了多种模式发生及转换的方法,将模式表征方法归结为非相干、相干和低相干测量法。光纤模式表征是目前的研究热点,在多种表征方法中,空间和频谱成像法（S2）和双重傅里叶变换法（F2）具有显著的优越性,可不需要提前知道光纤的几何参数,就可获得模场分布、模式功率占比、群时延等特性。研究表明F2法更适合于表征高功率光纤激光的模场特性。     

高精度动态光纤应变传感研究

传统的光纤应变传感技术无法在满足高精度和强环境适应性的同时实现稳定的动态应变传感.为了解决该问题,本文将光干涉原理应用于光纤应变传感,设计了一种强环境适应性的基于干涉结构的高精度光纤应变传感系统,基于扫频干涉信号的互相关系数,该系统可以稳定地探测应变.本文还提出一种动态探测算法,该算法弥补了系统只能探测较小应变的缺陷,大大提升了实际应变的探测范围,同时还实现了动态的应变检测;采用三次样条插值算法,提升了小应变探测的精度.理论分析和仿真模拟表明,在加入白噪声的信号信噪比为15dB时,插值后的探测精度是未插值探测精度的2.3倍,插值后本系统探测结果的最大误差只有约9nε.     

微机电光开关

对微机械光开关的特点和应用作了简要的论述 ,并对近年国外几种典型微机械光开关的结构、原理和研制方法作了简要的介绍和评述。这类新型的开关器件的主要优点是串话小 ,插入损耗小 ,消光比高 ,对波长和偏振不敏感 ,且体积小 ,造价低等 ,在光纤通信和光纤测试系统中具有广阔的应用前景