All-optical address recognition for optically-assisted routing in next-generation optical networks

Optical fiber communication technology enabled high-speed, long-distance capacity in today's networks. The packet switching functions such as address recognition and routing are performed in the electrical domain after optical-to-electrical conversion. As more real-time applications come online, demand for bandwidth increases, and electronic processing may potentially become a bottleneck at the intermediate nodes along the network. We introduce some optical address recognition schemes for optically-assisted routing that may decrease the processing delay at these nodes.     

All-optical timing extraction using an optical tank circuit

An ultrafast all-optical timing extraction method using an optical tank circuit is described, and experimental results at 2 Gb/s are reported. A Fabry-Perot resonator, whose free spectral range is equal to the clock frequency of the incoming optical data stream, is utilized as the optical tank circuit. Its fully passive structure and ultra-high-bit-rate operation (~Tb/s) is possible through decreasing resonator length     

All-optical routing using wavelength recognizing switches

This paper presents system considerations for optical packet-switched network using a wavelength recognizing switch (WRS) device for all-optical control and routing. Networks with the WRS device are capable of truly all-optical routing; the packet header is processed in the optical domain. This unique feature allows the self-routing of optical packets in a flexible and dynamically reconfigurable way, but introduces new challenges for the network architect. Our novel architecture combines the use of the WRS with arrayed waveguide devices in a powerful addressing mode. In this paper we explore some of the system issues, including crosstalk, noise performance, cascadability. We present experimental data on a broad-area WRS device we fabricated and assess the feasibility of an integrated version of the device     

All-optical multipoint-to-point routing in WDM mesh networks

In this article, the routing and wavelength assignment (RWA) problem for supporting multipoint-to-point communications in all-optical WDM mesh networks is investigated. Two efficient algorithms, namely reverse shortest path tree routing (RSPT) and k-bounded edge disjoint path routing (EDPR), are proposed. We proved that the problem of minimizing the total cost while establishing a multipoint-to-point session can be solved in polynomial time of O(|V|log|V|?+?|V|?+?|E|) by the RSPT algorithm, where |V| and |E| denote the number of nodes and the number of edges in the network, respectively. Nevertheless, the solution provided by the EDPR algorithm produces a significant reduction in the maximum number of wavelengths required per link (i.e., the link stress) for a multipoint-to-point session compared to RSPT algorithm. EDPR algorithm can also approximate to the optimal total cost with a ratio of k. Simulations are done to assess these two algorithms. Numerical results demonstrate their efficiencies in supporting multipoint-to-point communications in all-optical WDM networks.     

Lightpath routing for intelligent optical networks

An overview of current issues and challenges in lightpath routing for optical networks is given. An architecture is presented in which optical switches are deployed, usually in the core, to interconnect IP routers at the edges. Lightpath routing within this architecture follows the framework of generalized multiprotocol label switching. Our discussion pays particular attention to the aspects of optical routing that differ from routing in irrational IP networks. Such aspects include physical layer constraints, wavelength continuity, the decoupling of the control network topology from the data network topology, explicit routing with wavelength assignment, and diversity routing for fast protection. We also present an algorithmic framework for lightpath computation, highlighting the issue of wavelength continuity and the differences between lightpath computation and traditional IP route computation     

All-optical remote switching for multiplexed optical fiber sensorsand communications systems

All-optical self-routing switches are described which automatically route optical data signals. These switches require no separate source of power, and have been demonstrated to operate from a single input laser beam of 300 μW. The input laser beam contains the data, destination address, and optical power. These optical switches can be used for all-optical communication systems, and are used as an example in this paper to demonstrate remote switching via an optical fiber to a sensor. The sensor modulates the optical carrier which returns the modulated carrier to the source end of the fiber. The switch demonstrates auto-aligning properties which ensure correct rerouting of the modulated signal back to the source. Operation has been demonstrated for all the visible lines of an argon ion laser     

All-optical wavelength conversion in optical multicarrier networks

The authors analyze the use of all optical wavelength conversion in the optical layer of a high-capacity transport network and compare different technological solutions. The analysis is based on the evaluation of the transmission performance of a generic signal path through the network. At least two technologies have been discovered allowing the realization of all-optical wavelength converters suitable for use in the considered application, providing high performance. In particular, for networks covering long distances, wavelength conversion based on four-wave-mixing in semiconductor amplifiers seems to be a very interesting solution     

浅析IPv6网络地址分配与路由技术

在IPv4校园网络基础上快速部署IPv6网络。对IPv6的地址分配技术、路由技术进行具体分析研究,并结合Cisco和H3C两大品牌设备,给出配置方法。借助于认证系统的相关功能向客户机系统安装IPv6协议,并对IPv6地址的使用情况进行统计分析。     

Standards update: routing for optical networks

We focus on a component of the optical control plane: routing. We give a quick overview of what routing functionality can mean in the optical control plane and compare that with routing in IP networks. We also look at this functionality from the point of view of a carrier running an optical network. We point out some areas of potential disagreement and give an update of the status of optical routing at the various standards bodies.     

Issues for routing in the optical layer

Optical layer control planes based on MPLS and other Internet protocols hold great promise because of their proven scalability, ability to support rapid provisioning, and auto discovery and self-inventory capabilities and are under intense study in various standards bodies. To date however little attention has been paid to aspects of the optical layer which differ from those found in data networking. We study three such aspects which impact routing: network elements which are reconfigurable, but in constrained ways; transmission impairments which may make some routes unusable; and diversity. We conclude that if emerging optical technology is to be maximally exploited, heterogeneous technologies with dissimilar routing constraints are likely. Four alternative architectures for dealing with this eventuality are identified and some trade-offs between centralizing or distributing some aspects of routing are discussed     

All-optical tree-based greedy router using optical logic gates and optical flip-flops

Due to ever-increasing throughput demands, the lookup in conventional IP routers based on longest prefix matching is becoming a bottleneck. Additionally, the scalability of current routing protocols is limited by the size of the routing tables. Geometric greedy routing is an alternative to IP routing which replaces longest prefix matching with a simple calculation employing only local information for packet forwarding. For the first time, in this paper we propose a novel and truly all-optical geometric greedy router based on optical logic gates and optical flip-flops. The circuit of the router is constructed through the interconnection of SOAs and directional couplers. The successful functionality of the proposed router is verified through simulation. The circuit enables high data rate throughput.     

All-optical routing switch using a fiber nonlinear directionalcoupler and controlling solitons

A routing all-optical switch in which the signal, consisting of a fundamental soliton, is directed into either of the output ports of a 2×2 nonlinear directional coupler is investigated by means of computer simulation. The routing is controlled by copropagating a controlling pulse along with the signal pulse. Four different schemes for doing this are explored where the polarization of the controlling pulse with respect to the signal soliton may be varied, or the controlling pulse may be launched into either of the input ports, or it may have a wavelength different from that of the signal. It is shown that only one of the schemes allows a high switching efficiency and enables distortionless propagation of the signal pulse through the coupler     

All-optical signal processing based on semiconductor optical amplifiers

In this paper,we review the recent progress in the optical signal processing based on the nonlinearity of semiconductor optical amplifiers (SOAs).The four important optical signal processing functional blocks in optical switching are presented,i.e.,optical wavelength conversion,optical regeneration,optical logic,and optical format conversion.We present a brief overview of optical wavelength conversion,and focus on various schemes to suppress the slow gain recovery of the SOA and improve the operating speed of the SOA-based optical switches.Optical regeneration including re-amplification,re-shaping and re-timing is also presented.Optical clock recovery that is essential for optical regeneration is reviewed.We also report the recent advances in optical logic and optical format conversion,respectively.After reviewing the four important optical signal processing functional blocks,the review concludes with the future research directions and photonic integration.     

全光交换机的新功能

现在，运营商为了减少运营成本和增加收入，正在热衷于采用全新的、基于新一代光器件的智能型光网络。这些新器件能提供新功能和多种功能的集成。其中，一个较为典型的例子就是全光交换器件。交换机已经从原始的简单光学机械装置发展成具有新功能的高速光器件。新功能如动态可调光衰耗和光层组播等已经被引入到光交换器件中。表1将下一代光交换技术和传统光交换技术作了简单的对比。下一代光交换机的特点是性能更好、功能更丰富。性能上的改善将为更多的新应用架起一个宽广的平台（如图1）。其范围包括从网络新技术到全新的系统集成。光层保…     

全光传输-光放大器与光弧子通信

介绍了光纤放大器特别是掺铒光纤放大器（EDFA）的性能及其关键技术，并介绍了光弧子的非线性效应和特点，以及光弧子通信系统。     

光正交频分复用信号垂直泵浦全光波长变换研究

理论分析了一种基于垂直泵浦结构光半导体放大器(SOA)的偏振无关光正交频分复用(OOFDM)信号波长变换模型,实验证明了基于SOA-四波混频(FWM)的OOFDM信号波长变换的可行性,观测到OOFDM在SOA引入噪声而带来的信号劣化。实验成功实现了2.5Gbit/s光OFDM信号的波长变换,其误码率为1×10-3的接收机功率代价可以忽略,其极化敏感度小于3dB。     

空间激光通信网络中的全光相位再生技术

围绕空间激光通信网络中高速数据多跳传输应用需求,针对相位调制激光链路经过空间长距离传输后信号质量劣化的问题,研究了基于相位敏感四波混频参量效应实现二进制相位调制高速激光信号的全光相位再生技术。利用Matlab软件数值分析了全光相位再生系统的影响因素,并基于OptiSystem仿真平台搭建了全光相位再生系统。结合高轨-地面站空间激光通信系统链路预算,对速率为10 Gbit/s的DPSK信号光经背靠背、相位噪声劣化以及劣化后全光相位再生处理三种传输场景进了对比分析。模拟仿真结果与数值分析结果均表明,与劣化后未经再生处理的系统相比,全光相位再生处理后的系统误码率平均优化4个数量级,信噪比提升约3 dB,表明该空间激光通信全光相位再生技术可实现相位调制信号的全光相位再生,能够有效提升空间相干激光通信系统的性能,可以应用于空间高速激光通信网络中继节点处的全光数据中继等方向。     

All-optical signal processing technologies in flexible optical networks

Photonic Network Communications - All-optical signal processing has always been critical assistance for the flexible optical networks (FONs) development which realizes various signal processing...     

A frequent-pattern approach for optical networks routing planning

Optical burst switching (OBS) networks have been receiving much attention as a promising approach to build the next generation optical Internet. In the bufferless DWDM switching technology, burst loss that should be minimized is the key design parameter. One of the critical design issues in OBS network is how to plan the optimal routing path in order to minimize burst dropping due to network resource contention. This study proposes the burst frequent-pattern tree (BFP-Tree) approach to pre-determine a suitable routing path in the OBS network. The BFP-Tree approach essentially is a learning-based mechanism that is able to determine a suitable transmission path from the historical network transaction data. The experiment results show that the successful rates of routing paths obtained by the BFP-Tree approach are able to converge to those of the optimal results.