Upgrading Gigabit Ethernet with Multi-window CWDM Technique

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

通过以太无源光网的射频电视传送技术

论述了1550 nm射频电视(CATV)通道与1490 nm数据通道的相互干扰问题。针对1490 nm光波通过光纤中受激拉曼效应对1550 nm光波的非线性串扰和1550 nm光波通过粗波分复用(CWDM)分波器对1490 nm光波的线性串扰提出了理论计算公式,进行了定量分析和计算。结果表明,数据非线性串扰可使射频电视系统低频端的载噪比下跌9 dB;而在常规融锥型粗波分复用分波器情况下,射频电视线性串扰可使数据光接收机的光功率代价达到2.5dB。最后指出了克服串扰的方法,如以太空闲字符扰码和高隔离度粗波分复用等。     

Reconfigurable optical multiplexer based on liquid crystals for polymer optical fiber networks

In this work, different novel 3×1 multiplexer structures for being used in polymer optical fiber networks are proposed. Designs are compact, scalable, and of low consumption, capable of operating in a large wavelength range simultaneously 660, 850, and 1300 nm, due to the use of nematic liquid crystal cells. Light that comes from each input port is handled independently and eight operation modes are possible. Control electronics has been made using a programmable integrated circuit. Electronic system makes available the managing of the optical stage using a computer. An additional four optical sensors have been included for allowing the optical status checking. Finally, a polarization independent multiplexer has been implemented and tested. Insertion losses less than 4 dB and isolation better than 23 dB have been measured. In addition, 30-ms and 15-ms setup and rise times have been obtained. The proposed multiplexer can be used in any polymer optical fiber network, even in perfluorinated graded index one, and it can be specially useful in optical sensor networks, or in coarse wavelength division multiplexing networks.     

High-performance 850 nm vertical-cavity surface-emitting laser in Gigabit Ethernet network

High-performance oxide vertical-cavity surface-emitting (VCSEL) laser is fabricated, and its usefulness is demonstrated as a suitable transmitting light source at 850 nm operating wavelength for Gigabit Ethernet application. Utilization of barrier reduction layers reveals low-threshold current requirement for operation at high modulation bandwidth. The electrical and optical characteristics, measured from the fabricated VCSEL, are simulated for Gigabit Ethernet transmission. Data rates of 1.25 Gbps with a bit error rate of 10⁻¹¹ are achieved by the use of a specific multimode network simulator.     

单模光纤窄带波分复用器的研究

由组合波导理论出发，分析了超长耦合器合区光纤间的功率耦合特性以及器件的偏振特性，并提出了研制二段窄波分单模光纤波发复用器的新方法，在研制常规耦合器的工艺基础上，先后研制成功１３１０ｎｍ或１５５０ｎｍ单窗口窄带波分复用器及１３１０ｎｍ或１５５０ｎｍ双窗口等三种复用间隔约１４ｎｍ的窄带波分复用器，其波长隔离度大于２０ｄＢ，具有２～３ｎｍ的带宽，偏振灵敏度小于０．１ｄＢ，附加损耗小于０．５ｄＢ，这些参数     

Fast Restoration Based on Alternative Wavelength Paths in a Wide Area Optical IP Network

In this article we describe an experimental investigation of IP network restoration based on wavelength recovery. We propose a procedure for metro and wide area gigabit Ethernet networks that allows us to route the wavelength in case of link failure to another existing link by exploiting wavelength division multiplexing in the fiber. Such a procedure is obtained by means of an optical switch that is managed by a loss-of-light signal that is generated by a router in case of link failure. Such a method has been tested in an IP network consisting of three core routers with optical gigabit Ethernet interfaces connected by means of 50-km-long single-mode fibers between Rome and Pomezia. Compared with other conventional restoration techniques, such as OSPF and MPLS, our method -in very fast (20 ms) and is compatible with real-time TV services and low-cost chips.     

Design of Simple Wavelength or Polarization Filter/Combiner

We present an analytical and numerical analysis of a simple wavelength or polarization filter/combiner constructed from three single-mode rectangular waveguides. The device has the advantage of easy fabrication using existing planar light guide techniques and can be designed to discriminate between optical signals with distinct polarizations at a given wavelength or between signals at a fixed polarization with a wavelength separation of 9~nm or more. It is therefore well suited for CWDM metro-communication, local area network, sensor, or control applications.     

Fast Restoration Based on Alternative Wavelength Paths in a Wide Area Optical IP Network

Abstract

In this article we describe an experimental investigation of IP network restoration based on wavelength recovery. We propose a procedure for metro and wide area gigabit Ethernet networks that allows us to route the wavelength in case of link failure to another existing link by exploiting wavelength division multiplexing in the fiber. Such a procedure is obtained by means of an optical switch that is managed by a loss-of-light signal that is generated by a router in case of link failure. Such a method has been tested in an IP network consisting of three core routers with optical gigabit Ethernet interfaces connected by means of 50-km-long single-mode fibers between Rome and Pomezia. Compared with other conventional restoration techniques, such as OSPF and MPLS, our method -in very fast (20 ms) and is compatible with real-time TV services and low-cost chips.     

A NOVEL SCHEME FOR XGM WAVELENGTH CONVERSION BASED ON SINGLE-PORT-COUPLED SOA

A novel scheme for wavelength conversion based on cross-gain modulation (XGM) in single-port-coupled semiconductor optical amplifier (SOA), in which the input and output share one port, is brought forward. Experimental results and theoretical analysis show that this scheme can be achieved with simple implementation, high output extinction ratio and large input dynamic range. Based on this novel scheme, 2.5 Gbit/s wavelength up conversion with 12.8 nm span has been demonstrated with the output extinction ratio as high as 15 dB.     

Network Evolution Toward a Carrier-Grade Ethernet Transport Network

Abstract

In this article, an overview is presented about state-of-the-art Ethernet technology and its evolutions beyond local area networks into metropolitan and wide area networks as carrier-grade technologies. It will be shown that the Ethernet can be used to guarantee the performance of current transport technologies in terms of operations, administration and maintenance, quality of service, monitoring, and test capabilities in support of service level agreements; in particular, the Ethernet could replace current transport techniques, simplifying network design and reducing both capital and operational expenditures. The Ethernet data-plane evolution will also be presented, from the virtual bridged local area network up to provider backbone bridging traffic engineering, including the issues related to the control plane. Also indicated is a future scenarios dealing with close interworking with optical technologies. In conclusion, a summary is given of experimental activities carried out on the virtual private local area network service, a current Layer 2 technique that can be assumed as a first step toward a carrier-grade Ethernet, which show the implementation of reliable wide area networks based only on gigabit Ethernet transmission.     

A scheme of optical interconnection for super high speed parallel computer

An optical cross connection network which adopts coarse wavelength division multiplexing (CWDM) and data packet is introduced. It can be used to realize communication between multi-CPU and multi-MEM in parallel computing system. It provides an effective way to upgrade the capability of parallel computer by combining optical wavelength division multiplexing (WDM) and data packet switching technology. CWDM used in network construction, optical cross connection (OXC) based on optical switch arrays, and data packet format used in network construction were analyzed. We have also done the optimizing analysis of the number of optical switches needed in different scales of network in this paper. The architecture of the optical interconnection for 8 wavelength channels and 128 bits parallel transmission has been researched. Finally, a parallel transmission system with 4 nodes, 8 channels per node, has been designed.     

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.     

手掌静脉识别典型波长选择

目前的手掌静脉识别系统均采取主动光源来获取掌脉图像,光源波长的选择直接影响掌脉图像的清晰度与识别性能。典型的掌脉识别成像波长为760,850,890,940 nm,但没有指出哪种波长识别性能最佳。从两个角度解决此问题,从识别特征提取角度,建立了基于Fisher判别率的掌脉成像清晰度模型,对4种波长拍摄的掌脉清晰度进行比较;从特征匹配角度,以3种典型的生物特征识别算法对4种波长拍摄的掌脉图像进行识别性能比较。在包含4种波长共2400幅掌脉图像的自建图库中进行实验,模型选择和典型算法实验结果都表明,850 nm优于其他3种波长。证明了850 nm拍摄的掌脉图像的识别性能最佳。     

光折变LiNbO_3晶体中单光栅实现波长解复用方案

基于光折变LiNbO3晶体中体光栅的各向异性衍射特性,从理论上分析了利用单个体光栅实现波分解复用技术的方案.在此方案中,采用He-Ne激光束记录一个特定波数的光折变体光栅,就能够实现远程通信波长在1550 nm附近的波长解复用,理论上可以实现的解复用波段范围是从1400 nm到1650 nm.由于采用了各向异性衍射,衍射光和读取光的偏振方向互相正交,提高了信噪比;另外,方案中仅需记录单个光栅就可以实现波分复用,克服了多重光栅复用方案中记录时间复杂性的问题.     

Matched-Cladding Single-Mode Optical Fiber Optimized at 850 nm Wavelength

A single-mode optical fiber with quadratic curve index profile in core layer is introduced. The profile is optimized at 850 nm wavelength. The 850 nm bandwidth of this fiber can reach up to 2056.35 MHz.km. This fiber can be used at 850 nm, 1310 nm, and 1550 nm wavelength.     

Single-mode and tunable VCSELs in the near- to mid-infraredInvited Paper

Single-mode, long-wavelength vertical-cavity surface-emitting lasers (VCSELs) in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3μm are presented. This wide spectral emission range opens applications in gas sensing and optical interconnects. All these lasers are monolithically grown in the InGaA1As-InP material system utilizing a buried tunnel junction (BTJ) as current aperture. Fabricated with a novel high-speed design with reduced parasitics, bandwidths in excess of 10 GHz at 1.3 and 1.55 μm have been achieved. Therefore, the coarse wavelength division multiplexing (CWDM) wavelength range of 1.3 to 1.6 μm at 10 Gb/s can be accomplished with one technology. Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated. One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning. Micro-electro-mechanical system (MEMS) tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity. All these devices feature continuous-wave (CW) operation with typical single-mode output powers exceeding 1 mW. The operation voltage is around 1 - 1.5 V and power consumption is as low as 10 - 20 mW. Furthermore, we have also developed VCSELs based on GaSb, targeting at the wavelength range from 2.3 to 3.0 μm. The functionality of tunable diode laser spectroscopy (TDLS) systems is shown by presenting a laser hygrometer applying a 1.84-μm VCSEL.     

新型结构可调谐全光波长转换器的理论与实验研究

可调谐波长转换器是智能化光网络中的关键光电子器件. 提出了一种基于半导体光放大器的环形激光器实现连续可调全光波长转换的方案，建立了该方案的理论模型. 理论计算和实际测定了不同条件下波长转换的输出特性，实验结果与理论计算基本符合. 实验中实现了40nm范围内连续可调、转换速率为2.5Gb/s的交叉增益调制型波长转换. 关键词： 可调谐波长转换 半导体光放大器 环形腔     

Advanced multifunctional optical switch for multimode optical fiber networks

In this work, an advanced multifunctional optical switch based on multimode fibers is proposed. It can work as a 3 × 1 optical multiplexer/combiner, a 2 × 2 optical switch, a variable optical attenuator and a variable optical power splitter. All these functionalities can be developed in the same device without any hardware modification, only by using the proper ports and control electronics.The proposed switch has been developed for being used in the visible and near infrared wavelength range: 450–650 nm for optical fiber automobile applications, 650–850 nm for home broadband applications; and 850–1300 nm for multimode fiber access networks. Up to three different types of twisted nematic liquid crystal cells have been designed and fabricated for fulfilling these different wavelength ranges as part of the proposed device.The multifunctional switch has been implemented and experimentally tested. Crosstalk usually better than ? 15 dB at 532 nm, 660 nm and 850 nm, in any state has been measured. Switching is achieved at voltage levels of 4 Vrms. Fiber to fiber insertion losses when operating as a 2 × 2 optical switch, range from 10 to 15 dB within 200 nm wavelength range; with a non-optimized optics for collimation and coupling.     

A double wavelength DFB laser with an identical active area for CWDM

A novel distribute feedback (DFB) laser which gave two different wavelengths under two distinct work conditions was fabricated. The laser consists of two Bragg gratings with different periods corresponding to wavelength spacing of 20 nm in an identical active area. When driving current was injected into one of the different sections separately, two different wavelengths at 1542.4 and 1562.5 nm were realized. The side mode suppression ratio (SMSR) of 45 dB or more both for the two Bragg wavelengths were achieved. The fabricating process of the laser was just the same as that of traditional DFB laser diode. This device can be potentially used in coarse wavelength division multiplexer (CWDM) as a promising light source and the technology idea can be used to enlarge the transmission capacity in metro area network (MAN).     

Proposal for a New Dense Wavelength Division Multiplexing Filter Based on Two-Dimensional Photonic Crystal Ring Resonator

Abstract

A new optical filter design based on a two-dimensional photonic crystal ring resonator structure with an N-channel model is proposed in this article. This study also shows that modifying the scatter radius and the waveguide width can significantly improve the performance of the original structure, which can solve the mode mismatch problem for output waveguide. Here, an example of a 16-channel photonic crystal ring resonator is provided; wavelength spacing of 1.6 nm and a high quality factor Q of 6,000 were achieved. The optical filter would be a potential key component in the application of dense wavelength division multiplexer devices.