传感器用特种光纤

本文较全面地介绍了用于光纤传感器的各种光纤,开发传感器用特种光纤的主要技术途径,制作工艺及传感特性.它包括声学敏感光纤、磁敏光纤、低双折射光纤、圆双折射光纤、椭圆双折射光纤、线性双折射光纤、保偏光纤、偏振光纤、稀土离子掺杂光纤及特种材料多组份光纤及光纤光栅等.     

光纤信号衰减引起的网络故障的探讨

能引起网络故障的因素有很多,其中由光纤或光纤设备引起的占很大一部分,包括光纤、光纤跳线、光纤耦合器、光纤接头和光纤收发器等。在确定了是由光纤引起的故障后,按顺序排查设备,可以更高效地解决问题。     

光纤熔接技术

光在光纤中传输时会产生损耗,这种损耗主要由光纤自身的传输损耗和光纤接头处的熔接损耗组成。光纤自身的传输损耗是一个确定值,而光纤接头处的熔接损耗则与光纤的本身及现场施工有关。努力降低光纤接头处的熔接损耗,则可增大光纤中继放大传输距离和提高光纤链路的衰减裕量。     

光纤的机械可靠性及寿命评估北大核心

为了探究延长光纤机械寿命的关键技术,研究了光纤机械可靠性及寿命评估模型。影响光纤机械寿命的主要因素是光纤裂纹生成和光纤裂纹在应力腐蚀下不断生长。根据光纤机械强度计算公式以及光纤疲劳试验的威布尔分布特性,建立光纤筛选实验寿命评估模型。运用该寿命评估模型对OPGW(光纤复合架空地线)线路寿命进行模拟计算和评估,探究了延长OPGW线路寿命的关键技术。结果表明,提高光纤疲劳参数和降低光纤使用时的应力水平,均可显著提高光纤寿命。     

光纤传感技术的发展及应用

介绍了传光型光纤传感器与传感型光纤传感器的基本原理,阐述了强度调制型光纤传感器、干涉型光纤传感器、光纤光栅以及光纤声发射传感器的应用,提出了我国光纤传感技术存在的问题以及发展方向.     

光纤在激光医学治疗上的应用

激光医学治疗用激光器包括紫外、红外、可见光激光器,激光用光纤输出端形式包括点状、柱状、球状等;光纤在医学器械的应用包括光纤照明和激光传输,现今石英光纤、多组份玻璃光纤、聚合物光纤以及红外晶体光纤、氟化物玻璃光纤、红外空芯波导等在医学治疗有许多应用,其中石英光纤已在医学美容、手术治疗和光动力疗法等方面获得广泛应用,多组份玻璃光纤可应用于光炙仪、光热治疗仪、牙科光固化机、牙齿美白仪、光纤内窥镜等医疗仪器中,聚合物光纤POF可应用于光纤黄疸治疗仪、激光血管内外照射治疗中,光纤在今后的激光医学治疗中发挥更加重要的作用.     

锥形光纤在光纤传感和光纤激光器上的应用

介绍了近年来得到广泛研究的锥形光纤技术的发展现状,尤其是在光纤传感和光纤激光器上的应用.在光纤上直接拉制出的锥区可用于制作小型化、一体化、具有许多优良光学特性的光纤器件.锥形光纤按束腰直径和光纤拉锥区的长度比,可分为锐锥度光纤(锥区长度和锥区的束腰直径较接近)和缓锥度光纤(锥区的长度远远大于束腰的直径).锐锥度光纤可以制作Michelson或者Mach-Zehnder干涉仪可用来实现折射率传感器;同时它还可改变激光光斑的强度分布,获得平顶光斑输出.利用单模缓锥度光纤可以实现窄线宽可调谐滤波器;另外基于缓锥度光纤可以实现多模光纤至单模光纤的转换器.锥形光纤结构紧凑,制作简单、成本低,必将成为多种实用光纤器件的核心.     

单芯光纤与双芯光纤的耦合方法与耦合机制

通过将单芯单模光纤与双芯单模光纤熔接后在熔点处进行熔融拉锥,实现了单芯光纤到双芯光纤的功率耦合,解决了由于双芯光纤特殊结构引起的与光源、单芯光纤等直接耦合及监测所存在的问题.对单芯单模光纤与双芯单模光纤的耦合理论进行了研究,基于直接耦合理论与弱耦合理论建立了单芯单模光纤与双芯单模光纤的耦合方程,并就影响耦合光功率的因素进行了讨论.结果表明该理论分析方法能够有效地描写单芯光纤与双芯光纤耦合过程中光波的行为特征.     

光纤制导技术及器件的发展(待续)

光纤技术在有线制导武器方面的应用是光纤技术军事应用的一个重要方面.光纤制导技术具有信息传输容量大、抗干扰能力强、制导精度高、隐蔽性好等一系列优点.为此介绍了光纤制导的关键技术及其在光纤制导导弹、光纤制导鱼雷、光纤制导水下武器和诱饵中的应用和发展,指出制导光纤、制导光缆、制导光纤陀螺和制导光纤水听器的发展现状和趋势.     

光纤的机械可靠性及寿命评估

为了探究延长光纤机械寿命的关键技术,研究了光纤机械可靠性及寿命评估模型。影响光纤机械寿命的主要因素是光纤裂纹生成和光纤裂纹在应力腐蚀下不断生长。根据光纤机械强度计算公式以及光纤疲劳试验的威布尔分布特性,建立光纤筛选实验寿命评估模型。运用该寿命评估模型对OPGW(光纤复合架空地线)线路寿命进行模拟计算和评估,探究了延长OPGW线路寿命的关键技术。结果表明,提高光纤疲劳参数和降低光纤使用时的应力水平,均可显著提高光纤寿命。     

D-Net, A New Scheme for High Data Rate Optical Local Area Networks

The development of optical fiber point-to-point communications systems has generated substantial interest in the application of optical fiber to local area networks. The feasibility of using guided wave optical technology for local area networks is explored. Various network schemes, including Fibernet, Express-Net, and C-Net, are examined. A new scheme, D-Net, is disclosed which has the advantages of high efficiency, low bounded delay, simple protocol, and implementation flexibility.     

Ultrafast All-Optical Synchronous Multiple Access Fiber Networks

Two synchronous multiple access schemes, TDMA and CDMA, are proposed for fiber optic networks using optical signal processing. Network synchronization is achieved by using a central modelocked laser which also serves as the source for each station. The data are converted into a high-bandwidth optical signal using electrooptic modulators. The accessing schemes use optical fiber delay lines. The feasibility of these schemes is discussed.     

基于光纤差分相移键控的色散补偿方案的研究

为了研究光差分相移键控(DPSK)调制格式在光纤高速传输系统中的色散补偿, 利用色散补偿光纤(DCF)的色散补偿原理, 对40Gbit/s光纤传输系统进行色散补偿, 分析了40Gbit/s单通道光纤传输系统中3种DPSK调制格式信号的频谱特性; 仿真了3种码型的色散容忍度以及3种调制格式在考虑光纤的非线性下的色散补偿方案。结果表明, 光非归零码差分相移键控(NRZ-DPSK)信号具有最好的色散容忍度, 但其受非线性的影响比较大; 33%归零码差分相移键控(33%RZ-DPSK)信号的色散容忍度差, 但其色散补偿后的效果优于NRZ-DPSK; 而载波抑制归零码差分相移键控信号对色散和非线性效应都有较好的抑制; 3种DPSK调制格式均在对称补偿2方案中色散补偿的效果最佳。此仿真研究对光DPSK信号在光纤中的色散补偿具有参考意义。     

光通信技术的发展现状和趋势

简要介绍了光通信的发展现状、最新技术和发展趋势,着重在大容量、长距离、波分复用、光纤技术、光放大这几个光通信的标志性技术方面作了论述,并简要阐述了未来光传输方案。     

Novel schemes for local area network emulation in passive optical networks with RF subcarrier multiplexed customer traffic

This paper proposes two novel optical layer schemes for intercommunication between customers in a passive optical network (PON). The proposed schemes use radio frequency (RF) subcarrier multiplexed transmission for intercommunication between customers in conjunction with upstream access to the central office (CO) at baseband. One scheme employs a narrowband fiber Bragg grating (FBG) placed close to the star coupler in the feeder fiber of the PON, while the other uses an additional short-length distribution fiber from the star coupler to each customer unit for the redirection of customer traffic. In both schemes, only one optical transmitter is required at each optical network unit (ONU) for the transmission of customer traffic and upstream access traffic. Moreover, downstream bandwidth is not consumed by customer traffic unlike in previously reported techniques. The authors experimentally verify the feasibility of both schemes with 1.25 Gb/s upstream baseband transmission to the CO and 155 Mb/s customer data transmission on the RF carrier. The experimental results obtained from both schemes are compared, and the power budgets are calculated to analyze the scalability of each scheme. Further, the proposed schemes were discussed in terms of upgradability of the transmission bit rates for the upstream access traffic, bandwidth requirements at the customer premises, dispersion tolerance, and stability issues for the practical implementations of the network.     

An Optical Fiber Video System

A general discussion is made of optical fiber video systems from the viewpoint of system design concepts, transmission schemes, etc. Among possible analog CATV systems, the Higashi-Ikoma Project is reviewed as an optical fiber video system application. The essential components and basic technologies required for optical fiber video systems are reviewed. System performance is reviewed by considering some of the typical field trial conditions.     

Optical Coupling Methods for Cost-Effective Polymer Optical Fiber Communication

In this paper, we report cost-effective light coupling methods for polymer optical fiber (POF) communication. Here, we compare the various optical coupling schemes in detail. By optical simulations, we analyze the conventional light coupling schemes, namely the direct coupling, lens coupling, and lensed fiber coupling. The simulation studies reveal that a lensed fiber tip particularly at the receiver side improves the light coupling efficiency to a great extent. The optimized lensed POF design confers an 85% coupling efficiency. Lensed POFs are realized with two low-cost fabrication methods. The characterization of the lensed POF are carried out to evaluate the lensing properties and hence to optimize the fabrication process.     

Mining the optical bandwidth for a terabit per second

A significant part of optical-fiber capacity can be tapped now that optical amplifiers can boost many high-speed channels simultaneously. The erbium-doped optical fiber amplifier opened the floodgates to wide-bandwidth, all-optical schemes for multiplexing many wavelengths. Until the advent of the erbium-doped fiber amplifier, no practical all-optical amplifier existed. Optical signals were instead regenerated electronically to overcome the attenuation inherent in the silica fiber as well as other losses due to optical components along the line     

Excitation of the optical fiber by a holographic interconnection

The results of implementation of a holographic interconnection that allows coupling of optical radiation into a cylindrical optical fiber are presented. Two rectangular coherent radiating apertures are used as a light source with the wavelength λ = 514.5 nm. Optical schemes for recording a hologram in a lithium niobate crystal and the subsequent holographic coupling of radiation into an optical fiber are presented.     

雷达信号光纤传输系统

本文提出雷达信号光纤传输系统的两个设计方案,其中第一个方案采用数字信号与模拟信号分别传输的办法,第二个方案采用全数字传输。根据第一方案设计的系统已研制成功并应用于某型号雷达,第二个方案正在研制中,同时本文还对系统所使用的关键技术进行了论述。另外提出了几种适合长距离的雷达信号光纤传输方案。