An overview of FDDI: the fiber distributed data interface

Updating earlier efforts in previously published work, the author presents an overview of fiber distributed data interface (FDDI) technology and explores the basis for its success. Particular emphasis is placed on the technical specifications for an upwards-compatible version of FDDI, FDDI-II, which adds the capability for circuit-switched services to the packet services of the basic FDDI, thus creating an integrated services LAN     

Following the fiber distributed data interface

The fiber distributed data interface (FDDI) follow-on local area network (FFOL) work was initiated in February 1990 by Task Group X3T9.5 of Accredited Standards Committee (ASC) X3 to establish requirements and formal projects for a next-generation LAN. The background for startup of the FFOL project, including its requirements and current status, are presented. It is shown that the higher performance of FFOL and its ability to handle all FDDI data formats will allow its use as a backbone to existing FDDI installations. FFOL will also be used as a replacement for FDDI and other LANs when its higher performance is required     

FDDI: Understanding the fibre distribute data interface

This is the first of three articles focusing on FDDI. The definition and the applicable standards are covered herein; the hardware will be discussed in the following article, and the network management of FDDI will be discussed in the third.     

常用分布式光纤传感器性能比较

分布式光纤传感器在温度、结构健康检测及通信光缆故障诊断方面发挥着越来越大的作用.分布式光纤传感器种类有很多种,不同种类其测量原理和测试精度、范围等参数也不同.文章对九种常用的分布式光纤传感器作了介绍,并给出了一些商品化仪器的参数,最后将它们的优缺点进行了比较.     

单模光纤拉伸器分布式双折射特性实验研究

在偏振敏感光纤系统中,光纤双折射是重要的参 量。基于压电陶瓷的单模光纤(single-mode fiber,SMF)拉伸器是光纤系统中引入应变、光程或 相位变化等常用的器件,而少有人关注过光纤拉伸器引入的双折射特性。本文提出基于分布 式偏振分析的SMF拉伸器双 折射特性表征方法,结合全穆勒矩阵分析和光频域反射仪技术,可以得到SMF拉伸器缠 绕光纤的分布式双折射特性。实 验得到:在光纤拉伸器使用过程中,光纤双折射随驱动电压增大而增加;当光纤拉伸器缠绕 光纤表面不平整时,可引入更高 的基底双折射,且在施加驱动电压时,基底双折射增加更加明显;设计合适的拉伸机构和光 纤缠绕方法,能有效地避免光纤拉 伸器使用过程中双折射的改变,但可能会引入较强的基底双折射。本文研究结果对于在偏振 敏感光纤系统中使用光纤拉伸器时系统性能的评估及优化具有指导意义。     

光纤直流电流传感器模拟输出接口误差自动测试系统

为了准确评估光纤直流电流传感器模拟输出接口的测量误差,以PCI6221多功能数据采集卡为硬件平台,基于LabVIEW软件开发了一个模拟输出接口误差自动测试系统。其能够对光纤直流电流传感器模拟输出接口电压、标准直流互感器输出电压和温度传感器的输出信号进行数据采集和处理,具有实时数据显示和存储、历史数据查询与报表、局域网远端监测等功能。仿真实验结果表明,该系统运行稳定可靠,加快了光纤直流电流传感器的性能验证,具有较强的工程实用性。     

超短光脉冲通过分布式光纤放大器的传输特性

为了探讨超短光脉冲在分布式光纤放大器中的传输放大特性及影响因素,建立了光脉冲在光纤放大器中的基本传输方程,以掺镱光纤放大器为例,采用分步傅里叶变换法对放大器中光脉冲的演变进行了模拟,讨论了初始啁啾和增益色散的影响。结果表明,当光脉冲在分布式光纤放大器中传输时,光纤的色散、非线性效应均会影响脉冲的形状和频谱,光脉冲初始啁啾也会对脉冲的传输状态产生影响;对于宽频谱光脉冲,增益色散相当于一种损耗机制,应该考虑其影响。相关结果对光纤放大器的系统设计和优化具有一定的参考价值。     

Single-polarization operation of fiber distributed feedback (DFB)lasers by injection locking

This paper investigated injection locking characteristics of a fiber distributed feedback (DFB) laser operating in dual polarizations, and found that it could operate in a single polarization by injection locking. The locking bandwidth was less than 10 MHz, much narrower than DFB laser diodes as a consequence of longer cavity length and resulting longer photon lifetime. As a more practical method to realize single-polarization operation of the fiber DFB laser, we proposed self-injection locking with a polarization-selective optical feedback composed of a mirror and a polarizer, and demonstrated a stable single-polarization operation     

分布式光纤传感数据编码存储方法研究

现有分布式光纤传感数据存储方法由于节点分布较为广泛,节点故障致使数据丢失现象常有发生,无法适应现今分布式光纤传感技术的发展与应用,故提出分布式光纤传感数据编码存储方法研究.依据现今光纤传感数据存储需求,结合网络编码与云存储优点,搭建基于网络编码的数据云存储架构,以此为基础,选取纠删码形式对分布式光纤传感数据进行编码,以...     

分布式以及准分布式光纤传感器研究进展

针对光纤传感器的现状,简单介绍了分布式以及准分布式光纤传感器的特点、优势及应用领域,在此基础上列举了国内外在单参数与多参数技术要求下的最新研究成果,并对单参数分布式光纤传感器和多参数准分布式光纤传感器在改善光源、光纤结构及解调技术方面的研究进行了对比分析,最后对其未来发展趋势进行了展望.     

Analysis of distributed erbium-doped fiber amplifiers with fiber background loss

An accurate model for erbium-doped fiber amplifiers with fiber background loss applicable to the unsaturated gain regime is presented. Exact analytical solutions are derived for the output pump power, gain, and amplified spontaneous noise as a function of input pump power in the cases of unidirectional or bidirectional pumping. An exact relation is also derived between the pump threshold and the pump required for fiber transparency. Such expressions are particularly useful to model distributed fiber amplifiers and to determine the optimal fiber parameters corresponding to a given pumping scheme. As an example, the analytical solutions are used to study the pump power requirement for distributed fiber amplifiers unidirectionally pumped at 1.48 mu m, and to determine an optimum Er/sup 3+/ absorption coefficient.<>     

Error exponents for distributed detection of Markov sources

The paper considers a binary hypothesis testing system in which two sensors simultaneously observe a discrete-time finite-valued stationary ergodic Markov source and transmit M-ary messages to a Neyman-Pearson central detector. The size M of the message alphabet increases at most subexponentially with the number of observations. The asymptotic behavior of the type II error rate is investigated as the number of observations increases to infinity, and the associated error exponent is obtained under mild assumptions on the source distributions. This exponent is independent of the test level ϵ and the actual codebook sizes M, is achieved by a universally optimal sequence of acceptance regions, and is characterized by an infimum of informational divergence rate over a class of infinite-dimensional distributions. Important differences-due to the observations being Markov-between the asymptotically optimal distributed tests and their nondistributed counterparts are highlighted. The converse results require a blowing-up lemma for stationary ergodic Markov sources, which is also proven     

Temperature performance of Raman scattering in data fiber and its application in distributed temperature fiber-optic sensor

A wavelength division multiplexer (WDM) was used to extract the Raman scattering signal from a data fiber. The temperature performance of Raman scattering spectrum was studied theoretically and experimentally. On the base of this study, a distributed fiber-optic temperature sensor (DFTS) system was developed. The sensing distance was 4 km. The temperature accuracy and the distance resolution reached to ±1℃ and ±1 m, respec-tively. The system is stable and adequate for commercial usage, such as the power industry, the underground tunnel, the subway, and the pipe laying, and also for the mission applications, such as the warship and the airplane.     

BOTDR分布式光纤传感器研究进展

基于布里渊光时域反射(BOTDR)的分布式光纤传感器无论是在军用系统还是大型民用工程方面都具有广泛的应用前景.在给出BOTDR分布式光纤应力传感器的基本原理的基础上,详细介绍了国内外目前几种不同的BOTDR,并对其优劣进行了分析与比较.分析表明采用微波外差检测技术的BOTDR不仅具有较高的灵敏度,还具有更低的造价.     

Study of distributed erbium doped fiber amplifier

Basing on analyzing distributed erbium-doped fiber amplifier(d-EDFA) of evenly doped density along propagating direction, we put forward two sort d-EDFAs of slowly and linearly variously doped density along propagating direction: one-variation and two-variation d-EDFA. By using convective equations, we study the propagating properties of signal and noise in three sort d-EDFAs. Noise figure, signal-noise ratio, necessary pump and optimal pump period also are studied, under both transparent transmission and optimal doped density.     

分布式光纤喇曼放大器实验研究

为了对后向抽运分布式宽带光纤喇曼放大器的特性进行实验研究,采用多波长1426nm,1440nm,1460nm,1475nm和1495nm的半导体激光器作为抽运源,实现了C+L波段近80nm带宽的信号光放大,获得了比较好的平坦增益、偏振相关增益,系统平均开关增益为10.7dB,增益平坦度为1.5dB,最大噪声指数为-1.96dB,偏振相关增益小于0.4dB.结果表明,光纤喇曼放大器的抽运源波长、功率选择比较合理,系统所有技术指标均满足光纤通信使用要求.这一结果将对通信产业化发展有着重要的指导作用.     

分布式光纤喇曼放大器实验研究

为了对后向抽运分布式宽带光纤喇曼放大器的特性进行实验研究,采用多波长1426nm,1440nm,1460nm,1475nm和1495nm的半导体激光器作为抽运源,实现了C+L波段近80nm带宽的信号光放大,获得了比较好的平坦增益、偏振相关增益,系统平均开关增益为10.7dB,增益平坦度为1.5dB,最大噪声指数为-1.96dB,偏振相关增益小于0.4dB。结果表明,光纤喇曼放大器的抽运源波长、功率选择比较合理,系统所有技术指标均满足光纤通信使用要求。这一结果将对通信产业化发展有着重要的指导作用。     

Skew characteristics of image fiber for high-speed 2-D paralleloptical data link

Skew of an image fiber, which has more than ten thousands of cores in a common cladding, was measured by a novel measurement method for the first time. This method can measure the time-of-flight difference between individual cores over the whole area of an image circle. The measurement result reveals that a test 100-m-long image fiber has skew of 5 ps/m, and the time-of-flight distributes randomly in the whole area of the image circle due to nonuniformity of the core dimension. It is also experimentally shown that the skew of an image fiber increases by bending. The theoretical analysis reveals that the bending-induced skew depends neither on the radius of curvature nor the shape of the curve but it depends only on the number of turns it is wound. The numerical calculation of skew by using typical parameters of image fibers shows that the winding have to be restricted to less than five turns to achieve a transmission speed of over 1 Gb/s/ch. Finally, we propose a twisted image fiber and an “8-shaped” bobbin to suppress the skew due to bending     

Single-mode operation characteristics of a self-injection seededFabry-Perot laser diode with distributed feedback from a fiber grating

We study the operational characteristics of a self-injection seeded laser diode in an external cavity consisting of a fiber Bragg grating. The distributed feedback (DFB) of light in the grating provides an additional tolerance of frequency detuning in mode selection. The spectral characteristics at different operating frequencies and feedback rates have been investigated. Wavelength tuning has also been realized by applying compressive and tensile strain to the grating and a tuning range of 11.6 nm has been obtained     

Electrical characterization of interface states in Ni/n-Si(111) Schottky diodes from (C-V) characteristics

Experiments have been performed on Ni/n-Si(111) Schottky diodes fabricated by the vacuum vapor deposition of Ni at 10⁻⁵ Torr pressure on an n-type «111å oriented silicon wafer. Measured current-voltage and capacitance-voltage characteristics in range frequency range 10 kHz-1 MHz have been analysed. Interface states parameters have been extracted from (C-V) characteristics using a metal-thin interfacial layer-semiconduct (MIS) structure model. The interface states density has been found to be in the range of 10¹¹ cm⁻² eV⁻¹ with a peak in the band gap of Si at about 0·51 eV below the conduction band edge.