裂缝光纤传感的工程应用

光纤传感的灵敏性及工程"存活率"是其工程实用化的两个关键技术参量,对光纤-混凝土结构两种常用裂缝光纤传感光信号对裂缝宽度的灵敏性与存活率进行了实验研究,对光纤涂覆层对灵敏性影响的大小和机理进行了分析,并制作了灵敏性与存活率均较高的光纤试验样本,与裂缝成45°夹角时,相比于等直径的普通二次涂覆粗光纤(10/125/900μm),样本的灵敏性提高近65%,而存活率亦高出约15%。研究结果可为裂缝光纤传感的优化设计和工程应用提供了基本参照。

光纤涂敷层对光纤裂缝传感器分布式监测能力的影响

基于混凝土模型试验，对涂敷层的传感光纤的裂缝复用能力进行了定量分析，得到了传感光纤和工程结构裂缝夹角在30°，45°，60°时的复用能力与裂缝宽度的关系曲线。对由软性材料构成的光纤涂敷层来说，光纤的复用能力随涂敷层厚度的增加而增大，在与裂缝夹角成45°时，二次涂敷粗光纤的复用能力约为细光纤的5倍，表明光纤敷层对光纤裂缝监测的复用能力具有较大影响。对这种影响的机理进行了理论分析和试验研究，发现当混凝土开裂时，光纤沿混凝土界面的滑移是光纤涂敷层影响光纤裂缝复用能力的主要原因，在光纤与裂缝夹角成45°时，这一影

混凝土高坝裂缝光纤分布式监测能力的研究

基于单点裂缝模型试验结果分析,提出了一种利用瑞利散射的工程结构裂缝光纤监测复用能力的方法,得到水工混凝土裂缝光纤监测两种典型方案的裂缝复用能力,结合三峡工程泄洪坝段上游面出现的裂缝,进行了光纤裂缝传感复用能力的工程适用性分析,进一步揭示工程裂缝光纤分布式监测能力研究的意义.

大坝裂缝方位对光纤裂缝传感器灵敏性的影响

基于混凝土模型试验,对大坝裂缝方位的随机性对基于瑞利散射的光纤裂缝传感灵敏性的影响进行了定量分析,得到了传感光纤在大坝安全监控缝宽控制范围内,与裂缝夹角为20°、30°、45°、60°时的光纤灵敏性与裂缝宽度关系曲线。实验发现裂缝与光纤的方位角每增加15°,则光纤的灵敏性降低一半以上,这表明工程裂缝方位的随机性对光纤裂缝传感的灵敏性具有较大影响。对此影响的力学机理进行了分析,并提出相应的工程对策。

基于偏振度检测的光纤电流传感方案

本文提出了一种将光学谐振腔中多次来回反射所产生的法拉第旋转积累效应转化为光学信号偏振度变化的光纤电流传感方案。这种方案的主要优点是可以克服环境等因素的扰动带来偏振态变化所产生的影响。文中对所提出方案的特性进行了简单的理论分析和模拟计算，并给出了相应的实验结果验证。

Development of Microfluidic Devices with the Use of Nanotechnology to Aid in the Analysis of Biological Systems Including Membrane Protein Separation, Single Cell Analysis, and Genetic Markers

Computation technology has dramatically changed the world around us; you can hardly find an area where cell phones have not saturated the market, yet there is a significant lack of breakthroughs in the development to integrate the computer with biological environments. This is largely the result of the incompatibility of the materials used in both environments; biological environments and experiments tend to need aqueous environments. To help aid in these development chemists, engineers, physicists and biologists have begun to develop microfluidics to help bridge this divide. Unfortunately, the microfluidic devices required large external support equipment to run the device. This thesis presents a series of several microfluidic methods that can help integrate engineering and biology by exploiting nanotechnology to help push the field of microfluidics back to its intended purpose, small integrated biological and electrical devices. I demonstrate this goal by developing different methods and devices to (1) separate membrane bound proteins with the use of microfluidics, (2) use optical technology to make fiber optic cables into protein sensors, (3) generate new fluidic devices using semiconductor material to manipulate single cells, and (4) develop a new genetic microfluidic based diagnostic assay that works with current PCR methodology to provide faster and cheaper results. All of these methods and systems can be used as components to build a self-contained biomedical device.

Frequency upconversion properties of Er3+/Yb3+-codoped lead-germanium-bismuth oxide glasses

The frequency upconversion properties of Er3+/Yb3+-codoped heavy metal oxide lead-germanium-bismuth oxide glasses under 975 mn excitation are investigated. Intense green and red emission bands centered at 536, 556 and 672 run, corresponding to the H-2(1/2) --> I-4(15/2), S-4(3/2) --> I-4(15/2) and F-4(9/2) -->I-4(15/2) transitions of Er3+, respectively, were simultaneously observed at room temperature. The influences of PbO on upconversion intensity for the green (536 and 556 nm) and red (672 nm) emissions were compared and discussed. The optimized rare earth doping ratio of Er3+ and Yb3+, is 1:5 for these glasses, which results in the stronger upconversion fluorescence intensities. The dependence of intensities of upconversion emission on excitation power and possible upconversion mechanisms were evaluated and analyzed. The structure of glass has been investigated by means of infrared (IR) spectral analysis. The results indicate that the Er3+/Yb3+-codoped heavy metal oxide lead-germanium-bismuth oxide glasses may be a potential materials for developing upconversion fiber optic devices. (C) 2006 Published by Elsevier Ltd.

基于人工神经网络的大量程光纤实时距离干涉测量仪

提出了一种基于人工神经网络的全光纤化大量程实时距离干涉测量仪．采用双正弦相位调制方法，即通过同时调制半导体激光器的波长和干涉仪的光程差实现外差测量。为了扩大干涉仪的测量范围和消除输出信号中的交叉敏感，采用人工神经网络进行信号处理，把两路经过初步解调的干涉信号作为输入样本，物体距离的实际值作为输出样本，对神经网络进行训练，以使其具有良好的推广能力．实验结果表明神经网络的使用不仅扩大了距离的测量范围而且提高了测量精度．

消除正弦相位调制干涉仪中光强调制影响的全光纤干涉仪

在激光二极管(LD)正弦相位调制(LD-SPM)干涉仪中,通过注入电流调制激光二极管波长的同时,光源输出的光强也被调制,成为测量误差的主要来源之一。提出一种新的消除激光二极管正弦相位调制干涉仪中光强调制影响的干涉仪,给出了具体的理论分析。该干涉仪采用全光纤结构,有效减小外界干扰对干涉测量的影响;采用容易实现的前置信号处理电路和实时相位检测器对干涉信号进行处理,消除了激光二极管光强调制产生的测量误差;同时实现了物体微小位移的高精度实时测量,测量的重复精度达到1 nm。实验结果与其他消除光强调制影响的方法测得

基于光时域反射计的全分布式光纤漏油传感器

报道了一种基于光时域反射计的全分布式光纤漏油传感器,该传感器能实现分布式实时监测长输油管道,及时发现小型的漏油事件.传感器沿管道铺设,利用光时域反射计实时测量光纤在长度上的损耗变化特点,及时发现并定位管道上的每一处泄漏事件.模拟实验证明了其实际操作的可行性,长期使用的稳定性和各种抗干扰性,能在15min内发现并定位漏油事件,且定位准确度为3m.

Directly modulated wavelength-multiplexed integrated microring laser array

The first demonstration of a directly modulated microring laser array is presented for on-off keyed, wavelength- division- multiplexed fiber-optic data transmission. GaInAsP-InP microring resonators oscillating at separate wavelengths in the 1.5-μm band are vertically coupled to a common passive waveguide bus, which is fabricated on the reverse side of the InP membrane. Two microrings defined with radii for a wavelength channel separation of 6 nm have been assessed for both individual and simultaneous operation. Negligible power penalty (<0.2 dB) is observed for wavelength-division-multiplexed operation with and without transmission over a 25-km fiber span in a manner which indicates low crosstalk between the integrated sources. A device area of less than 0.12 mm2 per microring on a common passive bus allows a highly scalable solution for short-reach wavelength-multiplexed links. © 2008 IEEE.

40 Gb/s carrierless amplitude and phase modulation for low-cost optical datacommunication links

4 bps/Hz 40 Gb/s carrierless amplitude and phase (CAP) modulation is investigated for next-generation datacommunication links. The 40 Gb/s link achieves double the length of a conventional NRZ scheme, despite using a low-bandwidth source. © 2011 Optical Society of America.

MIMO system capacity improvements using radio-over-fibre distributed antenna system technology

The effect of antenna separation in a 3×3 MIMO system using RoF DAS technology is investigated. Larger antenna separation is found to improve the throughput due to reduced channel correlation and improved SNR. © 2011 Optical Society of America.

Monolithic electro-optically modulated VCSEL suitable for radio over fibre applications to 20 GHz

An integrated EOM VCSELs is shown to offer high linearity (92dB/Hz 2/3 at 6GHz) and by extrapolation ∼90dB/Hz2/3 up to 20GHz. Successful modulation with IEEE 802.11g signals is demonstrated at 6GHz with a 12dB dynamic range. © 2011 Optical Society of America.

Systems aspects of optical technologies for use in datacommunications

This paper reviews the development of system techniques using advanced modulation formats that have arisen in recent years for use in datacommunications. Simulations are provided to allow comparison of the emerging schemes. © 2011 Optical Society of America.