液氮温度光纤Bragg光栅的应变传感特性

对光纤Bragg光栅(FBG)液氮(77 K)下的应变传感技术及应变特性进行了研究.实验和分析表明:常温下FBG反射谱中的单个中心峰在低温下会劈裂为多峰,它产生于光纤、粘贴胶和金属基底热膨胀系数间的差异引起的强烈非均匀热弹性应变,使常温下均匀的光栅变啁啾化.建立了多种技术手段,成功消除了低温多峰现象,并测得了FBG低温和常温下的应变传感特性.实验结果表明:FBG的应变灵敏系数与温度无关.     

16通道光纤布拉格光栅解调系统的研究

鉴于单通道解调系统一次可检测的光栅波长数目有限,同时为兼顾FBG(光纤布拉格光栅)解调系统与上位机通信的稳定性与高速性,结合波分复用与空分复用技术,研制了多通道、多通信端口的FBG解调系统。通过控制16路光开关的光路切换,可实现对16通道FBG传感网的空分复用,对各通道传感器中心波长进行解调。测试结果表明,解调系统中心波长分辨率为1pm,一次采集光栅波长信息的时间为620ms,16个光通道的FBG传感信息更新最短时间不大于10s,可对约200只光纤光栅传感器进行有效监测。     

光纤光栅传感器阵列化与温度补偿研究

利用啁啾光纤Bragg光栅（FBG）反射和长周期FBG边沿滤波，提出并实现了一种综合的FBG传感快速解调方案。封装1对FBG进行应变差动传感、同时消除温度影响，不增加波长资源占用并使应变灵敏度得到有效提高，温度影响在很大范围内几乎为0。在全光纤化解调温度补偿型传感的基础上，研究了两路时分复用的设计方法，给出了时分链路间延迟光纤与光脉冲和解调端时分选通门的关系，实验结果与理论分析吻合。     

具有温度补偿功能的双匹配FBG振动传感系统研究

为了提高光纤Bragg光栅(FBG)振动传感系统的 解调灵敏度和解调范围,消除环境温度对解调信号的影响,设计了一种具有 温度补偿功能的双匹配FBG振动传感系统。系统采用两个中心波长对称地位于传 感FBG两侧的透射式匹配FBG,建立 了两个互补对称的传感通道,并利用差分原理实现振动传感。通过Matlab软件对系统性能进 行了仿真分析,结果表明,与传 统方法相比,本文方法有效地提高了系统解调灵敏度和解调范围。将匹配FBG与热电制冷器( TEC)集成封装,并建立温度补偿判断通道,当 判断通道输出电压超过已设置好的阈值时,利用TEC改变封装环境温度,使匹配FBG 与传感FBG中心波长重新匹配, 实现系统温度补偿。经实验测试,系统的归一化解调灵敏度为5.168/ nm,解调范围为1.2nm,判断通道的归一化阈值电压 为0.890。在4种不同环境温度下,利用本系统 对同一振动信号进行测量,实验结果验证了系统温度补偿的可行性。     

基于并联结构的M-Z型可重构光分插复用器

研究了一种具有模块化结构与升级能力的可重构光分插复用器(ROADM).每个模块由基于光纤布拉格光栅(FBG)的M-Z干涉仪(MZI)、1×2的光开关和Y型合波器构成.通过调整各模块中的光开关,该ROADM能够在1个下载端和上载端分别同时下路和上路任意单波长信号或多波长复用信号.设计并分析了4级并联的梯状式ROADM,由传输矩阵导出各种波长下载状态的路由控制表.实验结果表明,该ROADM能够减小输出功率不均衡的问题,在直通、下载和上载3种状态下的平均插入损耗均小于3 dB,信号间的隔离度大于20 dB.     

一种测量范围可调的FBG流速传感装置

基于锥形分速装置,研制了一种光纤Bragg光栅（FBG）流速传感器。利用FBG压强传感机构进行传感信号解调,同时利用开关控制流速管不同开孔的开闭状况。传感器的动态感测范围可达92．5-802．3mm／s,流速检测灵敏度为0．4mm／s,并且对温度不敏感。优化FBG压强传感机构及流速管的相关参量,能够进一步提高传感装置的...     

功率加权法用于光纤Bragg光栅特征波长检测

提出了一种用于光纤Bragg光栅(FBG)传感系统中反射波位移检测的算法.采用FBG反射波波长对光功率的加权平均作为特征值进行数据处理,用于FBG传感温度补偿系统中应变参量与温度参量的分离.研究结果表明:在光源扫描步长为50 pm时,使用该算法的FBG传感温度补偿系统的检测灵敏度达到传统中心波长法检测灵敏度的10倍左右.     

光纤光栅传感网络对桥桩结构的健康检测

基于对实验桥墩应变点分布的有限元法分析,设计了相适应的光纤Bragg光栅(FBG)传感网络。传感网络根据土层结构分10层布置,每层包括8个FBG应变传感器和1个温度补偿器。对桥墩进行自平衡静载荷实验,分12次完成,每次加载2350kN并持续2h,FBG传感网络实时监测不同载荷下桥墩桩结构的应变分布。监测结果表明:与传统的载荷-位移(Q-S)曲线方法相比,FBG传感网络在桥墩承载实验中能全程反映整体桩结构的变化,实现对桥梁的健康安全检测。     

光纤Bragg光栅高温传感技术研究

从温度传感理论模型的角度研究了光纤Bragg光栅(FBG)的温度传感特性,推导了封装后的FBG温度传感器的温度响应灵敏度系数的解析式,分析了FBG的高温响应特性,提出了在高温环境中降低FBG的非线性响应效应的方法.实验结果表明,提高基体材料的热膨胀系数能有效降低FBG传感器在高温环境中的非线性的影响.     

基于聚酰亚胺的FBG湿度传感特性及细观特征研究

实现了一种采用聚酰亚胺(PI)薄膜材料涂敷的光 纤布拉格光栅(FBG)湿度传感器,并研究了其表面涂覆结构、湿度传感特性、稳定性及迟滞 特性。采用新的PI溶液的制备工艺,提出了一种增强PI溶液与光纤栅区的耦合方法,并利用 扫描电镜(SEM)确定出4种典型的表面涂覆结构。实验结果表明,当FBG湿度传感器的PI涂覆 厚小于75μm时,湿度特性曲线拟合度大于0.99,标准差 小于0.5;温度特性曲线拟合度大于0.98,标 准差小于0.5;其中,45μm厚的FBG湿度传感 器 湿度灵敏度为7.9pm/%RH,误差度为2.19%, 迟滞性误差为2.6%,稳定时相对湿度波动范围小于0.8%RH。     

Experimental demonstration of an improved EPON architecture using OFDMA for bandwidth scalable LAN emulation

We propose and demonstrate an improved Ethernet passive optical network (EPON) architecture supporting bandwidth-scalable physical layer local area network (LAN) emulation. Due to the use of orthogonal frequency division multiple access (OFDMA) technology for the LAN traffic transmission, there is no need to change the existing EPON architecture. Only one receiver at each optical network unit (ONU) is required to detect both LAN traffic and EPON downstream traffic, which makes the proposed system simple and cost-effective. Moreover, flexible assignment of LAN traffic bandwidth is realized by allocating different number of subcarriers or using different modulation formats. The 250 Mb/s 4-quadrature amplitude modulation (4-QAM) and 500 Mb/s 16-QAM OFDM LAN traffic are successfully emulated with the EPON traffic in our experiment.     

多通道光纤加速度测试分析系统的研究

系统把微机电加速度敏感芯片与光纤传感技术相结合,技术上发展了基于微机电技术的光纤加速度传感器敏感部件的集成、批量制造技术;通过采用光开关和多组光同步分路器、分组切换电子开关和多通道同步数据采集器的组合,实现大容量测量通道数扩展。解决了传统光纤传感器向微型化和批量生产时遇到的装配困难及光纤传感器难以实现大容量高速同步采集的问题。     

EPON中安全机制的研究

基于以太网的无源光网络(EPON)是一个点到多点的系统,面临着很多安全隐患。针对EPON系统中存在的几种安全威胁,提出了一种解决EPON安全隐患的综合性方案。     

Remote management framework of home network based on EPON

As the extension of service provider network,the home network is the last section of the service delivery process, so it must have the characteristics of the operator network, that is, stable performance, manageable, maintainable, quality of service, security, and extendable.In this paper, with the integration of the new access network technology Ethemet passive optical network (EPON) and the remote network management protocol, TR-069 protocol, addressed by the Digital Subscriber Line (DSL)Forum, a remote management fiamework of home network based on EPON is presented.Then, a prototype system is also provided to realize the functions of TR-069 protocol on residential gateway.     

A photonic wavelength-division switching system using tunable laserdiode filters

A photonic wavelength-division switching system using semiconductor tunable wavelength filters is proposed. A switching system using wavelength switches and multistage switching networks is discussed. A crucial point in developing this switching system is to achieve a large number of wavelength-division channels. The potential of 100 wavelength-division channels in such switching systems is estimated, based on InP optical integrated circuits. A wavelength network synchronization which permits the network to utilize such a large number of wavelength-division channels without wavelength misalignment and drift is proposed. An eight-channel wavelength-division switching experiment, using phase-shift-controlled distributed feedback laser diodes as tunable wavelength filters, is reported     

分布式光纤传感技术与PON的融合

研究了分布式光纤传感以及无源光网络的原理、应用及关键技术,提出了将无源光网络与分布式光纤传感网络融合的思想,既可以克服局域网与骨干网之间的速率瓶颈,又符合光纤传感与光纤通信融合传输的发展趋势。针对分布式光传感技术在安防领域的应用与EPON的融合提出了解决方案,即将OTDR技术融入EPON中进行光纤故障监测与定位,实验证...     

Controllable multicast for IPTV over EPON

The character of 1 Gbps bandwidth and tree-based structure make Ethernet passive optical network (EPON) very suitable for broadcast or multicast services such as Internet protocol television video (IPTV). The document proposed a novel scheme, based on the former research for controllable multicast over EPON system, mainly considering system security and maintainability. It can both control the IPTV program source's and the receiver's validity, improving the efficiency and precision.     

Optical Interconnection Networks for Terabit Packet Switches

The challenge of building packet switches with terabit capacity is being met by wavelength division multiplexing (WDM) where the benefits of optical fiber are exploited. Two kinds of WDM-based bufferless optical interconnection networks are proposed in this paper to interconnect multiple electronic packet switch modules. One is based on 3-stage Clos principle and the other is based on broadcast-and-select principle. The proposed optical interconnection networks are implemented with small modular structures to provide capacities in the range of terabit per second. Their architectures, component and interconnection complexity, and power budget analyzes are presented. In addition, the crosstalk caused by the finite ON-OFF ratio of semiconductor optical amplifier is discussed. Bit error rates with respect to different ON-OFF ratios and extinction ratios are also evaluated. It is concluded that it is feasible to implement optical interconnection networks by using state-of-the-art WDM technology, and they are excellent candidates for future terabit packet switching systems.     

Novel access technology based on hybrid Ethernet passive optical network and Ethernet passive electronic network

To improve the limitations of Ethemet over Coax (EoC) technology in the bidirectional reformation of the hybrid fiber-coaxial (HFC) network, this paper proposes the concept of Ethernet passive electronic network (EPEN) based on multi-point control protocol (MPCP) and the hybrid access scheme of Ethernet passive optical network (EPON) and EPEN.This paper describes the network architecture of EPEN, and introduces the implementation scheme and design of the EPEN system.At present, the project group has been working on the core technology research and key software and hardware design of the EPEN system, on which we have accomplished the hardware design and debugging, the embedded software coding and debugging, the EPEN network management protocol design and software coding.However, there is still a lot to do to achieve networking capability, management, security, quality of service (QoS) and some other functions.     

Technology for extending transmission distance of EPON system

At present, the maximal transmission distance between the optical line terminal (OLT) and opticalnetwork unit (ONU) of an Ethemet passive optical network (EPON) system is 20 km.However, this distance should be extended to 50 km or even longer in some applications such as fiber to the village (FTTV).A method for extending the transmission distance of an EPON system is proposed in this paper, in which the optical power amplifier and the adjustment of dynamic bandwidth allocation (DBA) are the key technologies.