Upgrading Gigabit Ethernet with Multi-window CWDM Technique

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｗｉｔｈｔｈｅｓｐｒｅａｄｉｎｇａｎｄｄｅｖｅｌｏｐｍｅｎｔｏｆｄａｔａｔｒａｎｓｍｉｓｓｉｏｎｓｅｒｖｉｃｅｓ,ｔｈｅｒｅｑｕｉｒｅｍｅｎｔｏｎｎｅｔｗｏｒｋｂａｎｄｗｉｄｔｈｉｓｅｘｐｏｎｅｎｔｉａｌｌｙｉｎｃｒｅａｓｉｎｇ .Ｉｎｃｏｍｐｕｔｅｒｌｏｃａｌａｒｅａｎｅｔｗｏｒｋ (ＬＡＮ) ,ｔｈｅｄｏｍｉｎａｎｔｔｅｃｈｎｉｑｕｅｉｓＥｔｈｅｒｎｅｔ,ｗｈｉｃｈｉｎｔｅｒｃｏｎｎｅｃｔｓｎｅａｒｌｙ 80 ｐｅｒｃｅｎｔｏｆ ｐｅｒｓｏｎａｌｃｏｍｐｕｔｅｒｓ.Ｉｔｈａｓ…     

Upgrading Gigabit Ethernet with Multi-window CWDM Technique

In this paper, a new scheme has been proposed to achieve high-performance local area network adopting 5～15 nm separated coarse wavelength division multiplexing (CWDM) technique. Using this scheme, the current single-wavelength gigabit Ethernet can be seamlessly upgraded to multi-wavelength network. Not only can the network bandwidth be broadened, but also wavelength routing can be achieved among different sub-networks. The data packet communication latency can be reduced one-to-two magnitudes in comparison with that of the current gigabit Ethernet. To expand the network scale, multi-wavelength-window CWDM technique can be adopted. Two kinds of network interface cards have been designed using opto-electronics devices at the 850 nm and 1300 nm wavelength windows, respectively. Experiments indicate that the two kinds of CWDM signals can be selectively received at the corresponding optical detectors. By introducing two optical dropping devices in the network, multi-wavelength-window (850 nm, 1300 nm and 1550 nm) CWDM system can be achieved.     

光纤菲佐应变传感器的波分频分复用方法

将波分复用技术与空间频率复用技术相结合,提出了新的光纤菲佐应变传感器波分频分复用方法:在粗波分复用(CWDM)的不同波段实现具有不同腔长的光纤菲佐应变传感器的空间频率复用。描述了基于该方法的光纤菲佐应变传感器复用系统的结构、原理及实验结果,讨论了复用技术中可能产生的串扰的影响及其解决方法。实验结果表明,该方法大大提高了光纤菲佐应变传感器的复用能力,可复用40个以上的菲佐应变传感器,且其应变测量精度达±5με,可满足实际应用的要求。     

Analysis of physical layer performance of hybrid optical-wireless access network

The hybrid optical-wireless access network (HOWAN) is a favorable architecture for next generation access network. It is an optimal combination of an optical backhaul and a wireless front-end for an efficient access network. In this paper, the HOWAN architecture is designed based on a wavelengths division multiplexing/time division multiplexing passive optical network (WDM/TDM PON) at the optical backhaul and a wireless fidelity (WiFi) technology at the wireless front-end. The HOWAN is proposed that can provide blanket coverage of broadband and flexible connection for end-users. Most of the existing works, based on performance evaluation are concerned on network layer aspects. This paper reports physical layer performance in terms of the bit error rate (BER), eye diagram, and signal-to-noise ratio (SNR) of the communication system. It accommodates 8 wavelength channels with 32 optical network unit/wireless access points (ONU/APs). It is demonstrated that downstream and upstream of 2 Gb/s can be achieved by optical backhaul for each wavelength channel along optical fiber length of 20 km and a data rate of 54 Mb/s per ONU/AP along a 50 m outdoor wireless link.     

A Wavelength and Bandwidth Assignment Algorithm to Support Guaranteed Bandwidth Levels in Hybrid Time Division Multiplexing/Wavelength Division Multiplexing Ethernet Passive Optical Networks

Abstract

A novel bandwidth assignment algorithm in wavelength division multiplexing Ethernet passive optical networks, called a dynamic wavelength assignment service level agreement, is proposed to efficiently provide subscriber differentiation. Simulation results show that the dynamic wavelength assignment service level agreement outperforms other bandwidth allocation algorithms in wavelength division multiplexing Ethernet passive optical networks, as it makes a fairer bandwidth distribution than other methods and is able to overcome the non-allowed packet fragmentation of the Ethernet passive optical network standard. Consequently, it greatly increases the achieved throughput and always ensures a minimum guaranteed bandwidth to every priority subscriber. Furthermore, the new algorithm obtains lower mean packet delay and packet loss rate for the highest priority subscribers when compared with other bandwidth distribution schemes in wavelength division multiplexing Ethernet passive optical networks.     

基于磁光效应的二维三角晶格光子晶体模分复用器

随着全光通信的快速发展, 波分复用传输系统已不能满足高容量光网络的需求, 而模分复用技术利用有限的稳定模式作为独立信道传递信息, 可以成倍地提高系统容量和频谱效率, 是构建未来光网络的关键技术之一. 本文基于掺Bi复合稀土铁石榴石的磁光效应, 设计了1.55 μm波段的二维三角晶格光子晶体模分复用器. 在该光子晶体结构中引入缺陷, 形成模式分束波导, 通过外加磁场改变其在不同偏振模式下的磁导率, 从而控制TE, TM模式的传输, 实现了1.55 μm波段的模分复用. 利用平面波展开法和时域有限差分法对此模分复用器进行了能带和传输特性分析, 结果表明: TE和TM模式的透射率均高于92%, 信道隔离度分别为19.7 dB和42.1 dB. 这些特性在未来的大容量光传输系统中有着重要的应用前景.     

Control packet signaling mechanism using electronic code division multiple access for packet-based networks

We propose and experimentally demonstrate the feasibility of a control packet signaling technique using electronic code division multiple access for a wavelength division multiplexing packet-based network, whereby each wavelength channel is assigned a unique electronic code based label on a radio frequency subcarrier. Such a technique allows each wavelength channel to be electronically identified without requiring the use of a WDM demultiplexer. We experimentally demonstrate this technique with two wavelength channels each with 1.25 Gb/s baseband payload data and 10 Mb/s header coded onto an electronic code at 160 Mb/s. A performance study of the electronic code division multiple access based control signaling scheme in a wavelength division multiplexed packet-based access network is also performed in terms of the required power budget to monitor the electronic code division multiple access control signals in the presence of several sources of noise for error-free transmission of both payload data and electronic code division multiple access based control signals. It is shown that the modulation depth of each signal impacts the amount of required optical tap power. As the modulation depth of the electronic code division multiple access based control signal is increased, the required optical tap power is reduced. However, this increases the bit-error-rate for the payload data. Therefore, there lies a maximum and a minimum of the required tap optical power for the successful recovery of both signals. The lower bound of this range is usually determined by the successful recovery of electronic code division multiple access based control signal while the upper bound is determined by the successful recovery of payload data. The required optical tap power is analyzed for different transmission bit rates of the payload data for various receiver architecture scenarios without an optical amplifier at the receiver. The scalability analyses were repeated with an optical amplifier placed in the receiver terminal of the network. The resulting optical tap power that is required for the successful monitoring of the electronic code division multiple access based control signals are compared with that of the case without the amplifier.     

Multiaccess in all-optical networks with wavelength and code concurrency

A major obstacle in realizing fast packet switching in all-optical networks is the large tuning delays of tunable optical devices. This article proposes a multiaccess scheme for all-optical local area networks that employs both wavelength and code concurrency. In this scheme, several users share a wavelength channel through code multiplexing. The delay performance of hybrid wavelength/code division multiaccess is obtained under a simple, suboptimal access protocol based on cyclic search. Due to the reduction in the number of wavelength channels without an associated reduction in transmission concurrency, hybrid multiaccess is robust against tuning delays. At a given network throughput, the hybrid scheme achieves considerably lower delays than that of Wavelength Division Multiple Access even with a small amount of code concurrency. Conversely, the hybrid network can support a higher load when there is a maximum allowable value for the average packet delay.     

High-Efficiency Laser-Power Transmission With All Optical Amplification for High-Transmission-Capacity Submarine Cables

We present new trends in the performance evaluation of submarine fiber cable system with different ultrahigh multiplexing and propagation techniques over a wide range of the affecting parameters. Our model takes into account the ultimate optical transmission of huge submarine cables with 14,400 channels under different depth conditions. We employ Raman and erbium-doped fiber amplifiers in our study. We investigate the double impact of both temperature and pressure through the defined depth penalty. We also study the soliton transmission technique using two multiplexing methods considered in the design of ultra-wide wavelength division multiplexing (UW-WDM) with 14,400 optical channels and ultra-wide space division multiplexing (UW-SDM) with 440 fiber links. Based on experimental data, both the deep ocean water temperature and pressure are obtained as functions of the water depth.     

光互连技术在信号处理中的某些应用

叙述了近年来在天津大学研究及开发光互连网络的情况。这些研究围绕着解决信号传输中的延迟和通信带宽,开展的研究工作有：完成包括64个处理器的光电混合处理器阵列系统;giga—bit／s机群系统光互连链路;在链路中采用时分复用技术(TDM),实现了“虚拟并行传输”;在链路中设计了硬件路由功能,并组成光环网;在网络系统中实现波长路由,并建立了波长路由双环网,采用该技术可以避免路由延迟;在光互连网络中应用了MEMS光开关,实现了星型一环形二级结构;用同步光传输技术实现了多通道数据传输卡。     

Analysis of normalized throughput in WDM-based coherent time-spreading OCDMA system

The performance of normalized throughput in wavelength division multiplexing （WDM） based coherent time-spreading optical code division multiple access （TS-OCDMA） system is studied. The upper bound and lower bound of normalized throughput are obtained with 8 wavelength channels and 127-length Gold code, and with 4 wavelength channels and 511-length Gold code respectively. It is shown that when all simultaneous users are equally allocated to different wavelength channels, WDM＋TS-OCDMA has much better performance. However, if there is no central control to allocate wavelength channels equally, WDM＋TS-OCDMA system has the in-between performance of normalized throughput.     

Modeling and performance analysis of optical WDM node architecture using SRR protocol

In order to enhance the data transport capability and overall throughput of an optical wavelength division multiplexing (WDM) system, a proper node architecture design is necessary. In the present paper a simple node architecture model based on media access control protocols for bursty data traffic of variable time slot duration and data rate has been proposed to decrease the packet loss probability and to increase the efficiency of an optical WDM system using synchronous round robin (SRR) protocol. An appropriate mathematical model has been derived to evaluate performance of the proposed node architecture. It has been observed that the network performance is well controlled through implemented model and the corresponding network design parameters.     

Channel drop filter using photonic crystal ring resonators for CWDM communication systems

In this paper, a new optical channel drop filter (CDF) using photonic crystal ring resonators (PCRRs) is presented. Using the two-dimensional (2D) finite-difference time-domain (FDTD) method in triangular lattice photonic crystal (PC) silicon rods, 100% forward dropping efficiency and a quality factor of more than 1000 can be achieved in third communication window while the resonant wavelength is 1550 nm. Through this novel (CDF), a multi-CDF operation with 100% drop efficiencies across all channels can be obtained. The proposed device could be used in future coarse wavelength division multiplexing (CWDM) communication systems.     

Performance Analysis of Duty-Cycle Division Multiplexing over Wavelength Division Multiplexing System

Abstract

Performance optimization of a duty-cycle division multiplexing system over 8- and 40-channel wavelength division multiplexing networks is reported in this article. The modified duty-cycle division multiplexing system with optical domain multiplexing using a dual-drive Mach–Zehnder modulator is simulated with two and three users per wavelength. Using conventional dispersion compensation, the 40 × 40-Gbps system with two and three users per channel can support 240 and 160 km of transmission distance, respectively. The dispersion management technique based on a chirped fiber Bragg grating is proposed for a 40 × 3 × 13.33-Gbps duty-cycle division multiplexing/wavelength division multiplexing system that allows double the transmission distance compared to conventional technique.     

A novel proposal for all optical PhC-based demultiplexers suitable for DWDM applications

In this paper due to the crucial role of optical demultiplexers in wavelength division multiplexing and dense wavelength division multiplexing applications, we proposed a new mechanism for designing all optical photonic crystal based demultiplexers with 8, 16 and 32 output channels. Our proposed mechanism for wavelength selecting is a resonant defect structure which consists of one central defect and four defects around the central defect. It has been shown that the selected wavelength depends on the radius of the central defect and the distance between the central defect and other four defects. In all the three proposed demultiplexer the channels spacing is less than 1 nm. We used plane wave expansion method for extracting the band structure of the photonic crystal and employed finite difference time domain method for studying the optical properties of the designed devices.     

采用OFDM信号作为标记的光分组交换方案

以光正交频分复用信号作为光标记,利用两个不同波长的光载波分别经过强度调制,产生了10 Gb/sOOK光载荷和2.5 Gb/sOFDM光标记。测得了光分组信号经光纤传输前后接收载荷的眼图和标记的星座图以及误码率曲线,结果表明:经过40 km光纤传输后,载荷与标记的功率代价分别为1dB和0.5dB。     

Evolving the Optical Transport Network Management to Integrate Multiple Technologies and Services

Abstract

Optical networks are evolving at a fast pace from traditional synchronous digital hierarchy/synchronous optical network (SDH/SONET) and wavelength division multiplexing (WDM) infrastructures, used by client network layers in overlay mode, to a converged multi-service and multi-technology network able to transport traditional time division multiplexing (TDM) traffic and new packet traffic in a flexible way. Alcatel-Lucent is leading the network transformation required by network providers to offer data transport while guaranteeing the same quality and reliability typical of classical transport services. The introduction of new data communication services requires an evolution of the network management platform that needs to integrate new management applications associated with the new technologies and services. The resulting network has to be integrated from service provisioning and management system viewpoints to optimize its use and to reduce the in-field modifications of the transport network. This article describes specificities in the management of multi-service networks, identifying the management architecture able to support the rapid evolution of such environment.     

Spectral efficient hybrid wireless optical broadband access network (WOBAN) based on transmission of wireless MIMO OFDM signals over WDM PON

In this paper, a spectral efficient hybrid wireless optical broadband access network (WOBAN) is proposed and demonstrated based on the transmission of wireless multi-input multi-output orthogonal frequency division multiplexing (MIMO OFDM) signals over wavelength division multiplexing passive optical network (WDM PON). By using radio over fiber (ROF) techniques, the optical fiber is well adapted to propagate multiple wireless services having different carrier frequencies. It is a known fact that multiple wireless signals having the same carrier frequency cannot propagate over a single optical fiber at the same time, such as MIMO signals feeding multiple antennas in fiber wireless (FiWi) system. A novel optical single-sideband frequency translation technique is designed and simulated to solve this problem. This technique allows four pairs of wireless MIMO OFDM signals with the same carrier frequency for each pair to be transmitted over a single optical fiber by using one optical source per wavelength. The crosstalk between the different MIMO channels with the same frequency is eliminated, since each channel is upconverted on specified wavelength with enough channel spacing between them. Also the maximum crosstalk level between the different MIMO channels with different frequencies is very low around ?76 dB. The physical layer performance of the proposed WOBAN is analyzed in terms of the bit error rate (BER), error vector magnitude (EVM), and signal-to-noise ratio (SNR). The proposed WOBAN achieves 7.68 Gb/s data rate for 20 km for the optical back-end and 240 Mb/s for the outdoor wireless front-end.     

新型小尺寸窄带偏振分光器在光纤通信中的应用

在光纤通信中,为了在不改变调制波长范围的基础上仍能实现更多数据通道的波分复用,设计了一种新型的小尺寸窄带偏振分光器,用于对现有的数据通信网络进行扩容以及提高光信号的信噪比。在该分光器上蒸镀了两种新设计的膜系,一层是窄带滤光膜,另一层是偏振分光膜。采用TFCalc软件仿真,设计结果中窄带滤光膜的带宽约为0.4 nm,偏振分光膜在1 530～1 560 nm范围内对p光的通透性能优于99.8%。基于以上膜系设计在BK7光学玻璃上实际制备两组膜系,实验采用Agilent 8164-A型光波测量系统对经过膜后的光进行光谱分析。结果显示,窄带滤光膜的实际带宽优于0.4 nm,增益平坦度小于-0.05 dB,相比现有常见的0.8 nm滤光膜具有更窄的带宽,可以实现在调制波长范围不变的条件下增大波分复用的数据通道总量。偏振滤光膜的实际p光透光率为99.6%,相比仿真值略低,但仍优于设计要求,相比传统分光器的光信号强度保留效果更好,具有更高的信噪比。综上所述,该分光器具有更好的应用价值和实用意义。     

Dispersion Compensators Based on Overlaped Linearly Chirped Fiber Gratings for DWDM Systems

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　ＴｈｅｒｅｉｓａｇｒｅａｔｄｅａｌｏｆｉｎｔｅｒｅｓｔｉｎｆｉｂｅｒＢｒａｇｇｇｒａｔｉｎｇｓｄｕｅｔｏｔｈｅｉｒｍａｎｙｉｍｐｏｒｔａｎｔａｐｐｌｉｃａｔｉｏｎｓｉｎｔｈｅｆｉｅｌｄｏｆｔｅｌｅｃｏｍｍｕｎｉｃａｔｉｏｎｓａｎｄｆｉｂｅｒｓｅｎｓｏｒｓ .ＢｅｃａｕｓｅｆｉｂｅｒＢｒａｇｇｇｒａｔｉｎｇｓｅｘｈｉｂｉｔｄｉｓｐｅｒｓｉｏｎｂｏｔｈｉｎｒｅｆｌｅｃｔｉｏｎ ,ｅｓｐｅｃｉａｌｌｙｗｈｅｎｔｈｅ ｇｒａｔｉｎｇｉｓｃｈｉｒｐｅｄ[1] ,ａｎｄｉｎｔｒａｎｓｍ…