强场中光纤链路辐照损伤的计算与实验

北京正负电子对撞机重大改造工程中大量使用光纤传输数据.光纤链路中光纤及光收发元件等是在比较强的辐射场下使用,辐照会对其性能产生影响.为此,计算了在此辐射场中光纤的寿命,并利用实际辐射场测试光纤链路的辐照损伤,得出了传输误码率和光衰减等参数的变化规律,确保了光纤传输在工程中的可靠应用.     

基于物理地址编码的光纤链路智能识别

光纤链路的质量直接影响电力通信系统的工作性能,针对当前光纤链路识别方法存在识别误差大、实时性差等缺陷,为了降低光纤链路识别误差,设计了一种基于物理地址编码的光纤链路智能识别方法。首先对光纤链路识别原理进行分析,找到与光纤链路识别效果有关的重要因素,然后采用光纤物理地址编码技术对光纤链路节点进行编码,并构建光纤链路智能识别模型,最后在相同仿真环境下,与经典光纤链路识别方法进行对比实验,结果显示,方法较好地克服了当前光纤链路识别方法存在的局限性,光纤链路识别的智能化程度更高,改善了光纤链路识别效果,获得了比经典方法更优的光纤链路识别结果,实际应用价值更高。     

城域网中光纤链路传输问题的优化探讨

针对城域网各逻辑层中不同的光纤链路所传输信号特性差异,本文首先阐述了各链路现用传输技术的不足.并结合当前涌现的光纤传输新技术,着重探讨了城域网下一步建设及优化整合的解决方案.     

基于程控的光纤链路自动交换设计

针对当前光纤链路交换的特点,提出了一种基于程控的光纤链路自动交换技术,该技术利用程序控制发送光纤链路旋转,实现与其它光纤链路的对接,完成光纤链路的自动化交换,为全光网的实现提供了另一种途径。     

基于FTTH的光网络保护系统的研究

针对FTTH光纤线路的保护问题,提出了一种无源光网络光纤线路切换保护系统.光纤线路切换设备通过不同的光纤链路连接远端设备的两个光通信端口,当某一个与远端设备连接的分支光纤链路出现故障时,光纤线路切换设备通过连接备用的分支光纤链路,保障通信的及时恢复.实验结果表明,ONU能够在50ms内自动完成在光口1和光口2间的识别与光路保护切换,极大地提高了PON光纤线路保护的可靠性和生存性,有利于FTTH/B的应用.     

多段光纤链路中的FWM效率

通过推导由多段光纤构成的光纤链路中的四波混频(FWM)效率,找出了影响全光波长变换的FWM效率的因素,进而利用MATLAB软件成功模拟出任意多段光纤链路中的FWM效率.以由7段光纤组成的光纤链路为例,通过调节影响混频效率的各种参数的值,得到了获取最佳混频效率的参数取值范围,并可进一步获得稳定的波长变换效率.     

超稳光纤链路的理论与实践(续)

超稳光纤链路这个概念包含超稳频率光源和超稳频率传递的光纤链路.从当前看,如何利用已有庞大的公用电信网、专用网的光纤和光网络的资源,选择一个通用的光纤通路改造成超稳光纤链路来实现频率传递,取代基于卫星的频率传递,提高传输的频率精度,这是一个巨大的系统工程.本文对超稳频率光源和超稳频率传递的光纤链路的关键技术进行研究和讨论...     

超稳光纤链路的理论与实践

超稳光纤链路这个概念包含超稳频率光源和超稳频率传递的光纤链路.从当前看,如何利用已有庞大的公用电信网、专用网的光纤和光网络的资源,选择一个通用的光纤通路改造成超稳光纤链路来实现频率传递,取代基于卫星的频率传递,提高传输的频率精度,这是一个巨大的系统工程.本文对超稳频率光源和超稳频率传递的光纤链路的关键技术进行研究和讨论...     

多路调幅光纤在有线电视中的应用

本文从三个方面较为系统地论述了光纤有线电视的技术特点。链路构成对构成光链路的器件进行了分析对比；网络设计针对ＦＴＦ结构模式，提出了一般方法和指标分配要求；链路性能则对光纤的噪声及失真进行了一些定性和定量分析，最后讨论了光纤链路的失真改善因子。     

不同单模光纤组成的光缆链路的兼容性

单模光纤种类繁多,在光缆链路中不可避免地会出现不同类别光纤相互连接的情况.从模场直径、折射率、截止波长、衰减、色散、偏振模色散、非线性效应等方面分析了光纤混接后可能对链路性能的影响.并列出了各类光纤与兼容性相关的部分性能要求.     

25km光纤链路高精度频率传输实验研究

分析了影响光纤频率传输精度的主要因素,设计并 实现了一种新的基于锁相环(PLL)补偿的双向异频传输方案。首先,为了 确定光纤链路引入的不稳定性,设计了恒温条件下链路稳定性测试方案,通过光电联合测试 得出了链路传输指标;然后,结 合环境温度及PLL对光纤频率传输的影响,设计了环境温度影响下链路时延稳定性测 试方案,并搭建了实验平台;最后, 进行了光纤传输实验,分析了环境温度和阻尼系数变化对传输性能的影响。结果表明,由于 PLL的有效补偿,10MHz高 精度原子钟频率信号经过25km的光纤传输后仍能保持很高的稳定性;本文方案下的链路时 延抖动在环境温度慢变时可以稳定在0.5ns以内,显著降低了实际光 纤应用中传输时延的不稳定性。     

Progress in externally modulated AM CATV transmission systems

Recent advances in electronic linearization of AM CATV transmitters based on externally modulated diode pumped Nd:YAG lasers are presented. The theoretical principles and practical issues related to the methods of feedforward and predistortion linearization, the factors affecting system performance and the emerging devices, circuits, subsystems, and systems architectures are reviewed. In experiments based on a predistortion linearized system, transmission over two fibers of 30 km each, wherein each fiber carries 80 NTSC channels, is now routinely achieved with a CNR>50 dBc, a CTB<-65 dBc, and a CSO of typically -70 dBc. As the number of channels broadcast over each fiber is reduced from 80 to 60, CNR increases to 52 dBc. The fiber links served by the system under test each have 12-dB link budget, and include four connectors per fiber, with no degradation observed in one link when the connectors were opened on the other link     

ODN中光纤的宏弯损耗对ONU弱光的影响

通过对ONU弱光的ODN链路衰耗进行分析,发现ODN链路的下行衰耗严重超标的现象,在用OTDR进行故障定位、并测试光纤在相应波长的宏弯损耗后,得出光纤的宏弯损耗是导致ODN链路下行衰耗超标的原因;进一步对ODN链路的入户段光缆进行衰耗测试,从而验证了宏弯损耗是引起ONU弱光的主要原因。     

A femtosecond code-division multiple-access communication systemtest bed

This paper reports comprehensive experimental results on a femtosecond code-division multiple-access (CDMA) communication system test bed operating over optical fiber in the 1.5 μm communication band. Our test bed integrates together several novel subsystems, including low-loss fiber-pigtailed pulse shapers for encoding-decoding, use of dispersion equalizing fibers in dispersion compensated links for femtosecond pulse transmission and also in femtosecond chirped pulse amplification (CPA) erbium doped fiber amplifiers (EDFAs), and high-contrast nonlinear fiber-optic thresholders. The individual subsystems are described, and single-user system level experimental results demonstrating the ability to transmit spectrally encoded femtosecond pulses over a 2.5-km dispersion compensated fiber link followed by decoding and high contrast nonlinear thresholding are presented     

Investigations on the dominant dispersion penalties occurring inmultigigabit direct detection systems

The dominant penalties are wavelength chirp, line broadening due to optical back reflection, and mode partition noise due to insufficient side-mode suppression. Experimental results on pulse compression at 1550 nm and on penalty reduction by dispersion compensation are presented. The dispersion compensation is achieved by adding a negative dispersive fiber link to a standard fiber link with positive dispersion at 1550 nm. In this way it was possible to transmit 5 Gb/s over a 111-km fiber link     

Modal interference in a short fiber section: Fiber length, spliceloss, cutoff, and wavelength dependences

When a short fiber section is inserted within a fiber link, it is known that modal interference can create periodic oscillations in the wavelength dependence of the insertion loss and, accordingly, the insertion loss can exceed the sum of the interconnection losses (in decibels). This modal interference phenomenon is a potential cause of noise in telecommunications transmission systems. Experimental and theoretical investigations were performed in order to better understand its dependences on relevant fiber parameters and to generate engineering guidelines to minimize it in a telecommunication link     

On trading wavelengths with fibers: a cost-performance based study

We consider the effect of multiple fibers on wavelength division multiplexing networks without wavelength conversion. We study networks with dynamic wavelength routing and develop accurate analytical models to compare various possible options using single- and multiple-fiber networks. We use results of an analytical model and simulation-based studies to evaluate the blocking performance and cost of multifiber networks. The number of fibers required providing high performance in multifiber networks and their costs are compared. A case is made for using multiple fibers in each link with fewer wavelengths instead of using a single fiber with many wavelengths. In particular, we show that a network with four fibers per link and with four wavelengths on each fiber without any wavelength conversion on any node yields similar same performance as the networks with one fiber per link and 16 wavelengths per fiber on each link and with full wavelength conversion capability on all nodes. In addition, the multifiber network may also offer the cost advantage depending on the relative cost of components. We develop a parametric cost model to show that multiple fibers in each link are an attractive option. Finally, such multifiber networks also has fault tolerance, with respect to a single fiber failure, already built into the system.     

一种新型实用的光纤连接系统

本文提出了一种新型实用的乐器数字接口（MIDI）的光纤连接系统，用光纤替代电缆连接MIDI设备，解决了MIDI数字信号对音频信号的干扰问题，增加了MIDI信号的传送距离，指出了光纤在乐器数字接口连接方面有很好的应用前景。     

Strain evaluation of epoxy-cured fiber-optic connectors

Optical fiber connectors are passive components used to link two fiber links or a fiber link to a photonic device. One widely used type of fiber connector, a design that uses a thermally cured epoxy adhesive, has been evaluated via Bragg grating-based fiber strain sensors. Strain sensors were used to evaluate the strain incurred by the optical fiber as a result of installation and subsequent environmental testing. Preliminary mechanical modeling and a strain analysis using Bragg grating-based strain sensors are discussed. Since the strain sensors were not exposed to uniaxial loading, mechanical modeling was used to determine the optimum placement of the sensors and the expected response. Also discussed are ongoing studies to evaluate the viscoelastic behavior of the epoxy and its effect on the strain state of the connector assembly.