动态光网络中交叉相位调制和放大自发辐射噪声积累效应的传输代价

研究了动态密集波分复用(DWDM)光网络中直接调制-强度检测(IM-DD)系统中的交叉相位调制(XPM)和放大自发辐射(ASE)导致的动态噪声积累效应对高速光脉冲传输时的强度噪声影响,修正目前IM-DD系统中传输代价Q参数的计算公式.通过仿真分析了动态网络环境下两种噪声积累对动态光路径接收端误码率(BER)的影响,得出了XPM相位噪声与动态网络中光纤段长度、段数、波长信道间隔、链路ASE噪声等在内的链路参数之问的关系.对于动态光网络中链路的选择具有很好的参考价值.     

WDM光网络的光路传输质量估计算法

在波长路由WDM光网中,信号在路由与波长分配算法(RWA)选定的光路上传输．传输过程中引入的各种串扰和噪声使信号的传输质量受到损伤,信号质量不断下降,目的结点无法正确有效地接收光信号。通过定义合理的结点和传输链路模型．提出了一种考虑线性传输损伤的比特错误率估算方法．在光路建立之前预先估计WDM网络中将要建立光路的传输质量,以此作为网络优化设计过程中RWA算法选路的依据。通过网络仿真和实验验证了算法的正确性。     

OBS网络中基于扩展Benes矩阵的节点串扰分析

光突发交换(OBS)的提出,一定程度上满足了对高速业务的需求,但由于交换结构中光路器件自身的特性以及信号的相互作用,其内部存在严重的串扰问题,阻碍了通信的进行,极大地限制了光突发交换的性能。为了进一步研究OBS光网络节点结构中的串扰问题,仿真模拟了OBS网络中基于扩展Benes光交换矩阵的节点串扰情况,证明了OBS网络节点结构中,光交换矩阵本身、输入输出光纤数和每根光纤中的复用波长数都会不同程度的引起串扰的变化,从而影响整个光通信网络的质量。     

谐振式光纤陀螺调相谱检测技术中的光克尔效应

谐振式光纤陀螺(R-FOG)是基于Sagnac效应产生的谐振频率差来测量旋转角速率的一种新型光学传感器。信号检测技术和系统中存在的各种噪声对系统的检测精度有着重要的影响。基于调相谱检测技术的谐振式光纤陀螺系统中,除顺时针(CW)和逆时针(CCW)光路传播的光强不均匀会引入非互易相位差,使系统出现零漂外,顺时针和逆时针光路的调制系数也会引入系统零漂。光克尔效应引入的系统零漂与系统的真实旋转在测量时是无法区分的,因此成为主要的噪声之一。通过光波场叠加原理,推导得到调相谱检测方案下的谐振式光纤陀螺系统中,光克尔效应引起的系统零漂的解析表达式。依据光克尔效应产生的零漂不随陀螺转速的改变而变化,利用简单的开环系统,对光克尔效应引入的陀螺零漂进行了测试。     

镇村光纤联网时应注意的几个问题

随着光纤和光发、光收等光设备价格的下降 ,利用光纤长距离传输有线电视的优势相对同轴电缆来说越来越明显。目前 ,很多乡镇对距离较远的村几乎都采取了光纤联网的方式 ,大大提高了农村用户收看电视信号的质量和节目套数。现根据本人在镇村光纤联网设计、施工、调试开通过程中的体会提出一些注意事项。1　关于光节点位置的选择一般来说 ,离镇有线电视机房 1ｋｍ左右 (指干线距离 )的村可以被定为光纤联网村。在确定各村光节点位置之前必须先计算出光节点以下允许分配网传输的最长支干线距离。这个距离可以根据乡镇有线电视总体指标分配中分…     

干涉式光纤陀螺的偏振噪声分析

针对采用LiNbO3集成光器件的干涉式光纤陀螺结构特点，利用琼斯矩阵和相干矩阵建立了此类光纤陀螺光路传输系统数学模型。在此基础上进行了光路偏振噪声的理论分析，通过计算得出最大偏振误差表达式，讨论了光路器件的性能对陀螺偏振噪声的影响，得出消光比是影响结果的关键因子，并阐述了主要有效措施。     

超长跨距无中继光传输系统中远程增益单元的研究

远程抽运光放大技术已广泛应用于超长跨距光传输系统。在介绍超长跨距光传输系统远程抽运光放大技术的设计方案基础上,得出了远程增益单元的增益和噪声指数与远程抽运光放大系统输出光信噪比的关系。从选择掺铒光纤、采用反射镜和设计隔离器位置等三方面对远程增益单元(RGU)的结构设计进行了理论分析和实验研究,比较了不同方案下的远程增益单元的增益与噪声指数,通过优化光路设计,提出了不同抽运功率和信号光功率条件下的最佳远程增益单元光路结构。结果表明,选用低浓度的HE980掺铒光纤、采用高反射率和低插损的反射镜及设计合适的光隔离器位置,远程增益单元的增益和噪声指数能得到明显的改善。     

色散缓变光纤中皮秒孤子传输动力学研究

用变分原理推导出了色散缓变光纤中皮秒光孤子传输的动力学方程，理论 色散指数缓变光纤中光孤子的传输特性，理论分析与数值模拟一致。     

采用光相位共轭减少光孤子传输系统中的Gorden-Haus定时抖动

介绍了光孤子传输系统中。由于掺铒光纤放大器自发辐射噪声引起的Gorden—Haus定时抖动产生的机理。分析了利用光相位共轭法来减少G—H抖动的原理。推导了采用光相位共轭器的孤子传输系统的定时抖动简化计算公式，并通过实例计算验证了理论分析的结果，即在整个孤子传输系统总长的2／3处放置光相位共轭器后。就可以使得系统的均方定时抖动减小到原来的1／9。     

非平衡光纤Mach-Zehnder干涉仪偏振衰落及相位噪声分析

研究了非平衡光纤Mach-Zehnder干涉仪因两束干涉光偏振态变化引起的偏振衰落和相位噪声问题。运用波导耦合理论和光纤偏振光传输理论，通过详细的推导，得到非平衡光纤Mach-Zehnder干涉仪输出光强、可见度以及相位噪声的表达式，分析了干涉仪可见度、相位噪声与干涉仪输入光偏振态之间的关系，提出抑制偏振衰落和相移噪声的方法。     

全光网节点规模的分析

导出了光信噪比与光节点数量 ,掺铒光纤放大器 (EDFA)噪声系数 ,增益的关系公式 ,并分析了光节点数目与EDFA特性参数的关系。分析表明 ,当光节点中EDFAs设置成输入EDFA补偿节点损耗 ,输出EDFA补偿光纤损耗的工作方式时 ,要保持光信号的信噪比不低于 2 0dB ,则光节点数目最多为 19左右 ,改善EDFA的噪声系数对提高光节点数目的作用不大 ;如降低光节点内部损耗 ,优化两个EDFA的增益 ,可以最大程度地提高网络节点规模 ,网络节点数最大可达 5 6。     

Scalability of Optical Networks: Crosstalk Limitations

Optical networks represent a promising solution for the future high capacity and flexible transport network. This paper presents a model for the performance evaluation of optical networks with respect to linear crosstalk and accumulated spontaneous emission noise. The proposed model is intended for the evaluation of the crosstalk requirements on the devices needed to support an optical network with a certain number of nodes and with a given level of bit-error rate.     

光纤通信接收机放大器的等效噪声模型

许多光纤通信文献给出了如图1所示的光接收放大器的等效噪声模型。本文证明了这个等效噪声模型与原始噪声模型不等价，并且也不具有可测性。所以，这个等效噪声模型是不正确的，因而不宜采用。作者认为，在光纤通信接收机的设计中，噪声计算只是为了分析接收机的灵敏度，而不是用来确定最佳信号源电阻，因而可以不用等效噪声模型，直接用原始的噪声模型反而更简单和更精确。     

Architectural analysis of multiple fiber ring networks employingoptical paths

Analyzes the performance of various types of multiple fiber ring networks employing optical paths (OP's). The multiple fiber ring network architecture is suitable for achieving failure resilient networks that have extremely large bandwidth but are still upgradable against future increases in traffic. This architecture will overcome the limitation of conventional WDM rings in terms of network expansion capabilities, the number of nodes within the ring, and the number of OP's accommodated in the network. The generic node architecture suitable for multiple fiber ring networks is presented and functionality requirements are identified. The OP accommodation design algorithms that minimize the required node system scale are proposed. Based on the generic node architecture and proposed OP accommodation design algorithms, we evaluated the performance of several types of multiple fiber rings in terms of the required node system scale for rings under various conditions. The effect of the ring architecture (uni-/bidirectional rings), optical path schemes (wavelength path/virtual wavelength path), and different node connectivity patterns are demonstrated for the first time. The obtained results elucidate the criteria for selecting the most suitable multiple fiber ring architecture     

Effects of Optical Buffering on the Performance of Manhattan Street Networks

Multihop networks are strong candidates for the implementation of high-speed networks, ranging from back-plane networks for cluster computing to metropolitan-area networks. Besides using deflection routing for contention resolution, optical buffering may be used to enhance the performance of optical multihop networks and to reduce or even eliminate the need for optical-electrical conversions. The enhancements obtained by augmenting traditional MSN (Manhattan Street Networks) with optical buffering are evaluated. The MSN considered here is based on a novel 6 × 6 optical switching node with up to two fiber delay loops. Impact of the parameters associated with optical buttering, such as the number of delay loops and the loop length, are discussed in detail.     

光分组网节点结构研究的现状与演化趋势

介绍了光分组网和光分组交换技术,从技术角度分析了光分组交换方式的优点,比较并评价了具有代表性的几类光分组交换节点结构,展望了光分组交换的前景及光网络节点结构的演化趋势。     

Provisioning Methods for Bit-Rate-Differentiated Services in Hybrid Optical Networks

This paper addresses the problem of routing and wavelength assignment of bit-rate-differentiated optical services in a hybrid network. Hybrid optical networks are composed of resources, such as fiber links and photonic/electronic switches, that vary in their capabilities and transmission qualities. These networks are also responsible for the realization of optical services with varying quality-of-service (QoS) guarantees. In such networks, it is required to have a cost-effective assignment of the optical and electronic resources to these services in order to maximize the revenue of the network operator. This paper deals with optical services that are defined according to their tolerance to transmission impairments. We first divide the provisioning problem into two phases: (1) routing and (2) wavelength assignment and regeneration reservation. In the routing phase, a set of k-routes are generated to select from in the second phase, where each route optimizes a specific aspect of the problem (e.g., number of hops, maximum accumulated noise, etc.). The second phase, using the information about the resources along each route, attempts at finding the best wavelength allocation on that route such that the signal quality meets the service-level agreement (SLA). The second phase also uses the minimum number of regenerator ports on intermediate nodes for the purpose of wavelength translation and signal clean-up. Comparisons of the above scheme with a probing-based method, reveal substantial enhancements to the blocking performance with a maximum running time increase of 60%. In addition, the use of multiple routes provides higher reduction in the blocking probability over single-routing schemes. Moreover, the proposed, non-pessimistic, provisioning approach has a major impact on reducing the regeneration budget of the network.     

自动交换光网络中的节点技术

本文首先通过对几个典型产品的描述，回顾了自动交换光网络节点技术的发展，然后归纳出自动交换光网络节点的功能要求和属性，之后，从不同方面对光节点进行分类整理，并重点论述光交叉连接器的六种基本结构以及一种多颗粒度的通用结构，最后综述了所涉及到的光电子器件，尤其是微机电系统（MEMS）光开关。     

Optical performance monitoring for the next generation optical communication networks

Today’s optical networks function are in a fairly static fashion and are built to operate within well-defined specifications. This scenario is quite challenging for next generation high-capacity systems, since network paths are not static and channel-degrading effects can change with temperature, component drift, aging, fiber plant maintenance and many other factors. Moreover, we are far from being able to simply “plug-and-play” an optical node into an existing network in such a way that the network itself can allocate resources to ensure error-free transmission. Optical performance monitoring could potentially enable higher stability, reconfigurability, and flexibility in a self-managed optical network. This paper will describe the specific fiber impairments that future intelligent optical network might want to monitor as well as some promising techniques.     

基于光纤环的光缓存器

提出了一种基于光纤环的光缓存器的结构,对结合半导体光放大器作光开关的此结构的物理模型进行了详细描述,并根据此模型分析了其增益、噪声、信噪比等方面的特性.