LiNbO3声光可调谐滤波器(AOTF)在OADM中的应用

基于LiNbO3晶体的声光可调谐滤波器(AOTF)是利用TE/TM模式转换的原理实现了多波长选择特性和宽调谐范围,这使它在波分复用(WDM)中的光分插复用(OADM)系统中有广泛用途.文章介绍了AOTF的基本原理,以及用它构成的OADM系统.     

集成声光与MEMS法布里-珀罗可调谐滤波器的研究

光交叉连接(OXC)与光分插复用(OADM)是下一代WDM光网络中两项关键的光节点技术,可调谐滤波器是其中的核心器件之一.本文结合863课题与自然科学基金课题,介绍了集成声光可调谐滤波器(IAOTF)与MEMS法布里-珀罗(FP)可调谐滤波器的主要性能、关键技术问题和我们的工作进展.     

LiNbO3声光可调谐滤波器(AOTF)在OADM中的应用

基于LiNbO3晶体的声光可调谐滤波器（AOTF）是利用TE／TM模式转换的原理实现了多波长选择特性和宽调谐范围，这使它在波分复用（WDM）中的光分插复用（OADM）系统中有广泛用途，文章介绍了AOTF的基本原理，以及用它的构成的OADM系统。     

快速波长可调的光插／分复用器

波分复用(WDM)是高容量光纤传输网络最有效的办法之一，而实现可重构WDM网络的核心器件是波长可调的光插／分复用器(OADM)。这样的器件必须具有较高调谐速度、宽的调谐范围、低的插入损耗、窄的信道带度、低的功耗、偏振独立性、简单的控制机构，以及小的尺寸。     

集成化光上下路复用器的研究进展

密集波分复用(DWDM)已经成为光纤通信的主要发展方向,光上下路分插复用器(OADM)作为WDM网络中的关键技术,它的优劣将直接影响通信网络的性能.侧重于从器件的角度对OADM的功能和发展现状进行介绍,并对其构成的关键器件的发展进行了概述.     

密集波分复用系统中集成声光器件的设计及系统实验

研究了集成光学声光可调滤光器(IAOTF)光开关和均衡器在波分复用（WDM）系统中的应用特点,并提出了对器件设计的要求和一些关键的设计方法,并给出了实验结果.实验结果表明,综合技术指标满足了WDM网络的实际应用要求,器件设计和制作方法是成功的.     

偏振无关集成声光可调谐滤波器及其应用

偏振无关集成声光可调谐滤波器(IAOTF)不但具有驱动功率低、调谐范围宽、插入损耗低以及可实现多波长同时选择等优点,还实现了输入光的偏振无关特性,在全光网络中极具应用潜力.文章设计了一种基于模分离器的偏振无关IAOTF,分析了它的基本结构及工作原理,并介绍了它在可调谐掺铒光纤激光器(EDFL)、光谱仪以及光开关中的应用.     

集成液晶可调谐RCE光电探测器的实验研究

实现了波长调谐范围为 8nm的集成液晶可调谐谐振腔增强型 (RCE)光电探测器 ,并且对相应的实验结果进行讨论。这种器件可用在波分复用 (WDM)光网络中     

基于LOBS的WDM光网络的组播研究

光波分复用(WDM)网络是一种广泛应用的光网络,而在WDM网络中实现组播应用是光网络的一个研究热点.文章介绍了这种网络的结构以及特点,重点讨论了目前国内外在WDM网络组播研究中的最新进展,并提出了基于LOBS的WDM网络的组播协议.     

OXC/OADM关键技术及其发展

由于WDM技术的飞速发展,用于构建WDM全光网络的设备——光交连接和光分插复用引起人们广泛关注。为此,文章对OXC/OADM的关键技和解决方案进行了介绍,并对OXC/OADM的发展进行了展望。     

Wavelength conversion and call connection probability in WDMnetworks

Call connection probability in an all-optical network using wavelength division multiplexing (WDM) depends on the number of WDM wavelengths and on the network capability for wavelength conversion at network nodes. New closed-form expressions for call connection probability are derived which reflect these dependencies. These expressions are combined in a converter availability model to study the impact of wavelength conversion on call connection probability and the tradeoff between network wavelength conversion capability and the number of WDM wavelengths     

Integrated acoustooptic tunable filters using weighted coupling

A detailed theory and experimental results are presented on weighted-coupling integrated acoustooptic tunable filters (IAOTF). A low-sidelobe-level single-stage IAOTF in which the weighted coupling was facilitated by focused surface acoustic waves along an interaction length of 6.0 mm has been realized on a Y-X LiNbO₃ substrate, 8 mm in length. The measured performances of this weighted-coupling IAOTF at the optical center wavelength of 1.31 μm include a peak mode conversion at the acoustic center frequency of 214.6 MHz, a wavelength tuning range of 110 nm, a -3 dB optical bandwidth of 4.1 nm, and a switching rise time of 0.965 μs. Sidelobe levels below -21.4 dB have been accomplished at the mode-conversion efficiency of 15 percent and an RF drive power of 160 mW     

All-Optical Wavelength-Bypassing Ring Communications Networks

We introduce an all-optical WDM packet communication network that performs wavelength bypassing at the routers. Packets that arrive at a wavelength (optical cross-connect) router at designated wavelengths are switched by the router without having their headers examined. Thus, the processing element of the router is bypassed by such packets. For packet traffic that uses wavelengths that do not bypass a switch, the headers of such packets are examined to determine if this switch is the destination for the flow. If latter is the case, the packet is removed. Otherwise, the packet is switched to a pre-determined output without incurring (network internal) queueing delays. We study a ring network with routers that employ such a WDM bypassing scheme. We present methods to construct wavelength graphs that define the bypassing pattern employed by the routers to guide the traffic flows distributed at each given wavelength. Performance is measured in terms of the network throughput and the average processing path length (i.e., the average number of switches not being bypassed). For a fixed total processing capacity, we show that a WDM bypassing ring network provides a higher throughput level than that exhibited by a non-bypassing ring network, using the same value of total link capacity. By using WDM bypassing, the average processing path length (and thus the packet latency) is reduced. We study a multitude of network loading configurations, corresponding to distinct traffic matrices and client-server scenarios. Higher throughput levels are obtained for network configurations driven by non-uniform traffic matrices. The demonstrated advantages of WDM bypassing methods shown here for WDM ring networks are also applicable to more general network topological layouts.     

Wavelength reuse for efficient packet-switched transport in an AWG-based metro WDM network

Metro wavelength-division multiplexed (WDM) networks play an important role in the emerging Internet hierarchy; they interconnect the backbone WDM networks and the local-access networks. The current circuit-switched SONET/synchronous digital hierarchy (SDH)-over-WDM-ring metro networks are expected to become a serious bottleneck-the so-called metro gap-as they are faced with an increasing amount of bursty packet data traffic and quickly increasing bandwidths in the backbone networks and access networks. Innovative metro WDM networks that are highly efficient and able to handle variable-size packets are needed to alleviate the metro gap. In this paper, we study an arrayed-waveguide grating (AWG)-based single-hop WDM metro network. We analyze the photonic switching of variable-size packets with spatial wavelength reuse. We derive computationally efficient and accurate expressions for the network throughput and delay. Our extensive numerical investigations-based on our analytical results and simulations-reveal that spatial wavelength reuse is crucial for efficient photonic packet switching. In typical scenarios, spatial wavelength reuse increases the throughput by 60% while reducing the delay by 40%. Also, the throughput of our AWG-based network with spatial wavelength reuse is roughly 70% larger than the throughput of a comparable single-hop WDM network based on a passive star coupler (PSC).     

Multiple-star wavelength-router network and its protection strategy

A wavelength division multiplexed (WDM) multiple-star network and its accompanying path and router protection strategies are proposed for interconnecting N major switch nodes in a national-scale telecommunications network. For a single path failure and uniform traffic matrix, fiber requirements are shown to be less than for a WDM ADM ring, while providing greater resilience to multiple path failures. “Adding” and “dropping” only whole wavelength channels between node pairs is found to lead to severe design instabilities and overinvestment in fiber, and time-sharing of wavelength channels is recommended to minimize fiber quantities. A star network capable of interconnecting N=22 switch nodes and an all-optical path protection switching method are verified experimentally, using a 16-channel 2,5-Gbit/s WDM system and a 22×22-port bulk-optics wavelength multiplexer as the hub router. Protection switching speeds within 50 ms are projected for a national-scale network     

Flexible hybrid WDM/TDM PON architectures using wavelength selective switches

For building an optical access network, we propose some new hybrid WDM/TDM passive optical network (PON) architectures that use wavelength selective switches (WSSs) at the remote node to improve flexibility, data security and power budget. Through simulations we demonstrate that the switching capabilities of a WSS can provide additional gains in terms of wavelength usage by a better statistical multiplexing. Several WSS-based hybrid WDM/TDM PON variants are proposed and assessed. These architectures are also compared with the more commonly used hybrid WDM/TDM PONs consisting of power splitters and/or arrayed wavelength gratings (AWGs), in terms of cost and power budget.     

全光波分复用网络技术

全光通信网和波分复用技术是目前国内外网络技术研究的前沿。尤其是将两者结合起来的全光波分复用网络更是研究的热点。本文着重从网络特性方面对整个全光波分复用网络技术的基本原理，技术，发展真挚和研究热点等作了全面的阐述，并对其中的关键总是作了较为详细的分析。     

Survivable traffic grooming with non‐service‐interruptive wavelength retuning in a WDM mesh network

This paper proposes a new survivable traffic grooming wavelength retuning (STGWR) scheme in an all‐optical wavelength division multiplexing (WDM) network. In a dynamic WDM network, a connection may require a bandwidth less than a wavelength capacity. In addition, a connection should be protected against any network failures. Survivable traffic grooming (STG) can protect connections at subwavelength granularities. Wavelength retuning is a promising approach in an all‐optical WDM network, where a signal must remain on the same wavelength from its source to the destination, to alleviate the wavelength continuity constraint and reduce the connection blocking probability. Although both STG and wavelength retuning have attracted extensive research attentions nowadays, no effort has been made to combine these two promising approaches in one network. In this paper, we propose a wavelength retuning scheme with no service interruption in an all‐optical network with STG capability. The scheme allocates two routes, one for the active path and other for the backup path, in a shared mesh restoration manner to each incoming connection request and conducts wavelength retuning only on the backup path. Both wavelength retuning and mesh protection are done at the connection level instead of at the lightpath level. The simulation results of the proposed schemes are also presented. Copyright © 2008 John Wiley & Sons, Ltd.     

Performance analysis of multicast routing and wavelength assignment protocol with dynamic traffic grooming in WDM networks

The need for on‐demand provisioning of wavelength‐routed channels with service‐differentiated offerings within the transport layer has become more essential because of the recent emergence of high bit rate Internet protocol (IP) network applications. Diverse optical transport network architectures have been proposed to achieve the above requirements. This approach is determined by fundamental advances in wavelength division multiplexing (WDM) technologies. Because of the availability of ultra long‐reach transport and all‐optical switching, the deployment of all‐optical networks has been made possible. The concurrent transmission of multiple streams of data with the assistance of special properties of fiber optics is called WDM. The WDM network provides the capability of transferring huge amounts of data at high speeds by the users over large distances. There are several network applications that require the support of QoS multicast, such as multimedia conferencing systems, video‐on‐demand systems, real‐time control systems, etc. In a WDM network, the route decision and wavelength assignment of lightpath connections are based mainly on the routing and wavelength assignment (RWA). The multicast RWA's task is to maximize the number of multicast groups admitted or minimize the call‐blocking probability. The dynamic traffic‐grooming problem in wavelength‐routed networks is generally a two‐layered routing problem in which traffic connections are routed over lightpaths in the virtual topology layer and lightpaths are routed over physical links in the physical topology layer. In this paper, a multicast RWA protocol for capacity improvement in WDM networks is designed. In the wavelength assignment technique, paths from the source node to each of the destination nodes and the potential paths are divided into fragments by the junction nodes and these junction nodes have the wavelength conversion capability. By using the concept of fragmentation and grouping, the proposed scheme can be generally applied for the wavelength assignment of multicast in WDM networks. An optimized dynamic traffic grooming algorithm is also developed to address the traffic grooming problem in mesh networks in the multicast scenario for maximizing the resource utilization and minimizing the blocking probability. Copyright © 2011 John Wiley & Sons, Ltd.     

波长转换对抗毁多光纤网状WDM网络的性能影响

目前研究波长转换器对WDM网络性能影响的文献一般都是针对单光纤网络并且不考虑网络抗毁的要求。该文使用整数线性规划建模和动态系统仿真的方法,分别研究了静态业务和动态业务下,多光纤网状WDM网络在满足抗毁要求时,节点配置波长转换器对网络性能的影响,以此对使用波长转换器获得的好处给出较为全面的结论。