Comparison Study on Three Different Reconfigurable Optical Add Drop Multiplexer Architectures

In this paper, we present the evolution of reconfigurable optical add drop multiplexer（ROADM） technologies, and compare three main ROADM architectures available on the market today. Three archhectures include broadcast-select and demux-switch-mux[and the integrated version planar lightwave circuit（PLC）] and wavelengths-selective switch.     

ROADM全光交换网络关键技术发展与应用展望

介绍了可重构光分插复用器(reconfigurable optical add/drop multiplexer,ROADM)网络的发展历程、ROADM技术方案以及国内ROADM网络的部署情况。全面阐述了ROADM关键技术的发展方向,包括光交叉连接(optical cross-connect,OXC)设备、高维度波长选择开关(wavelength selected switch,WSS)、波长无关/方向无关/竞争无关ROADM(colorless/directionless/contentionless ROADM,CDC-ROADM)、400 Gbit/s FlexGrid ROADM、下一代波长交换光网络(next-generation wavelength switched optical network,WSON2.0)智能控制平面技术。分析了现有ROADM网络应用场景与技术发展趋势,展望了ROADM全光交换网络未来发展前景。     

基于3 μm-SOI的波分复用/解复用器与电吸收型VOA的单片集成

波分复用/解复用器与可调光衰减器的是光通信系统中的重要元器件。为了得到制备工艺简单、响应速度快的二者的单片集成芯片,并且考虑到其与其他不同光器件的集成可能性,在绝缘体上硅材料制作了16通道、信道间隔200 GHz的阵列波导光栅复用/解复用器与电吸收型可调光衰减器的单片集成。该器件的片上损耗小于7 dB,串扰小于-22 dB。电吸收型VOA在20 dB的衰减量下的功耗为572 mW （106 mA,5.4 V）。此外,该器件可以实现光功率的快速衰减,在0~5 V的外加方波电压下,VOA上升及下降时间分别为50.5 ns和48 ns。     

光开关矩阵技术及其应用研究

光开关矩阵是智能光交叉连接设备和可重构光分插复用器核心技术,是构建自动交换光网络的基础.文章介绍了大规模商用的光开关矩阵的关键技术及其进展,详细分析了光开关矩阵在自动交换光网络中的应用.     

Novel node upgradation strategy for migration to elastic optical networks

For migration from dense wavelength division multiplexing (DWDM) networks to elastic optical networks (EON),it is required to upgrade the traditional reconfigurable optical add-drop multiplexer (ROADM) to the new-generation ROADM that supports flexible grids.However,for a large-scale optical network,it is generally impossible to upgrade the ROADM nodes all in once; rather,they would be upgraded gradually.For this,it is critical to study different strategies for selecting the ROADM nodes to be upgraded.Also,for the interconnection between different generations of ROADM,the sub-band virtual concatenation (VCAT) technique was employed to enable an optical channel to be established via traversing different types of nodes.An integer liner programming (ILP) model and an efficient heuristic algorithm were developed to jointly select the ROADM nodes to upgraded and assign spectrum resources.Simulation studies show that the proposed strategy for the upgraded node selection is efficient to perform close to the ILP model in terms of the maximum number of FS used in the whole network.     

光可变衰减器的研究进展

光可变衰减器(VOA)作为波分复用(WDM)网络中关键的功率管理器件,能够实现信道均衡和自动增益控制功能.微电机械系统(MEMS)型和热光型VOA以其衰减范围宽、功耗低、体积小、易于集成等优点成为研究重点,热光特性极佳的聚合物材料则成为最引人注目的热光材料.文章对已有的VOA器件作了概括分类,介绍了各种MEMS型VOA,还从热光材料的角度,总结了聚合物材料的研究成果,对已见报道的基于聚合物的各种热光型VOA进行了重点的描述和分析.最后给出了VOA的两种网络实例.     

广播与选择型ROADM的设计与实现

文章对动态可重构光分插复用器（ROADM）进行了介绍;对实现ROADM的多种方案进行了归纳整理和简要分析;对其中解复用／开关矩阵／复用（DSM）、DSM波段、广播与选择（B＆S）3种典型的ROADM结构进行了较详细的说明。文章作者设计并实现了广播与选择型ROADM,井对实验系统的上／下路功能和信道功率均衡功能进行了验证。     

Digital optical networks using photonic integrated circuits (PICs) address the challenges of reconfigurable optical networks

To reduce costs and simplify operations, carriers are deploying flexible optical networks that can be easily reconfigured and managed remotely. This article provides an overview of typical all-optical reconfigurable optical add/drop multiplexer (ROADM) systems and their associated network issues. We describe a novel digital optical network architecture based on digital ROADM systems, which use photonic integrated circuits (PICs) to overcome many of these issues. Digital ROADM systems use monolithic PICs to integrate over 60 discrete optical components, including lasers, modulators and detectors, into a single pair of optical components, allowing cost-effective optical-electrical-optical conversion at every node. This also allows key functions such as service reconfiguration, add/drop and protection to be implemented in the digital domain, and enables de-coupling of service provisioning from optical link engineering, termed bandwidth virtualization. Finally, key deployment, reliability and operational metrics for PIC-based digital ROADM systems are presented.     

光开关矩阵在自动交换光网络中的应用

自动光交换网络是光网络的发展趋势,其核心技术是光开关矩阵。光开关矩阵是智能光交叉连接设备和可重构光分插复用器核心技术,是构建自动交换光网络的基础。主要介绍了大规模商用的光开关矩阵的技术特点及其在自动交换光网络中的应用。     

Variable optical attenuator for large-scale integration

A polymer thermooptic variable optical attenuator (VOA) was designed and demonstrated for dense waveguide device integration. The waveguide bend design is compatible with photolithography fabrication techniques and operates by controlling waveguide bend radiation loss. The design optimizes the compromise between integration capability, integration cost, and attenuation efficiency. For a 5 mm bend length, optical attenuation of >40 dB has been achieved with an applied electrical power of 250 mW. The fiber-to-fiber insertion loss was 1.5 dB for a 20-mm total waveguide length. The design's compact size makes it practical for both VOA arrays and dense integrated optical circuits     

基于SOI的16通道VMUX器件单片集成

本文制作了基于绝缘体上硅(SOI)材料的16通道的光功率可调波分复用器(VMUX),并且采用了脊形波导结构。该器件是由信道间隔100GHz的阵列波导光栅(AWG)及电光型可调光衰减器(VOA)组成,该VOA采用了侧向p-i-n二极管结构。该VMUX器件的插入损耗为9.1dB,串扰为10dB。VOA在衰减量为20dB时的注入电流为60.74mA。器件的整体尺寸为2.9×1mm2。该VMUX器件具备优异的16通道波分复用及光功率均衡的性能。     

Polymer Planar‐Lightwave‐Circuit‐Type Variable Optical Attenuator Fabricated by Hot Embossing Process

A polymer‐based planar‐lightwave‐circuit‐type variable optical attenuator (VOA) was fabricated using a hot embossing process. With an optimized one‐step embossing process, forty micro‐channels for the guidance of light were defined on a polymer thin film with an accuracy of ° 0.5 µm. The fabricated polymeric thermo‐optic VOA shows 30 dB attenuation with 110 mW electrical input power at 1.55 µm. The rise and fall times are less than 5 ms.     

MOSAIC: a multiwavelength optical subcarrier multiplexed controllednetwork

The experimental demonstration of MOSAIC, a reconfigurable WDM add/drop network with subcarrier multiplexed control, is presented. The MOSAIC network implements the optical layer protocol to support bit-rate transparent multichannel lightpaths. Two types of add/drop multiplexers are implemented and combined in a three-node experiment. Multihop lightpaths are established giving an end-to-end bit error rate of better than 10^-9 at 1.2 Gbps. The reconfigurable add/drop multiplexer is based on a novel dilated 2×2 acoustooptic filter switch crossconnect and an analog optoelectronic crossconnect that drives a ten-wavelength laser array transmitter up to 2.5 Gbps per wavelength. The fixed wavelength add/drop multiplexer utilizes a fast digitally tunable laser transmitter. Both add/drop multiplexers support bit-rate transparent 2R optoelectronic regeneration as well as wavelength translation. Subcarrier multiplexing on each wavelength is used to support channel state monitoring and channel equalization as well as transmission of digital network control information. Systems experiments demonstrate cascaded 2R optoelectronic regeneration with wavelength translation and cascaded multichannel optical switching with up to seven hops. It is shown that combining cascaded 2R optoelectronic regeneration with cascaded multichannel optical switching can be used to balance jitter accumulation and amplified spontaneous emission generated amplitude noise to yield high signal-to-noise ratio for lightpaths     

多通道数字可调光衰减器模块的设计与实现

设计了一种基于电控可调光衰减器(EVOA)的多通道数字可调光衰减器模块,该模块集成多达32通道的光衰减器,可根据需要灵活进行配置,并采用了通用的I2C通信接口,非常方便和简单地应用于系统设备中.该模块克服了EVOA电压衰减非线性的缺点,衰减精度高,而且保留了EVOA的光学特性.     

ROADM设备网管系统的实现

可重构的光分插复用(ROADM)设备是光传送网的重要节点,通过软件配置,可以灵活实现波长上下,使网络具备重构功能.建立基于SNMP协议的网元管理系统是保证ROADM设备稳定灵活工作的前提,文章简述了ROADM设备的功能结构,并讨论了设备网管系统的建立和配置功能的软件实现.     

Optical Module Using Polymer Waveguide With Integrated Reflector Mirrors

A practical optical transmitter was prepared using a polymer waveguide with integrated reflector mirrors. The optical transmitter module consisted of a metal optical bench, a module printed circuit board, a driver integrated circuit, a vertical-cavity surface-emitting laser array, and an optical waveguide composed of integrated reflector mirrors. The cost-effective and repeatable technology for the integration of a polymer multimode waveguide and out-of-plane 45deg reflector mirrors was developed for optical coupling between the light sources and the waveguide. The data transfer measurements of the optical module were presented successfully at a data rate of 10 Gb/s.     

可调谐滤波器在DWDM系统中的应用

可调谐滤波器是实现未来全光网络的重要器件,在DWDM系统中有着广泛应用.文章介绍了几种常用的可调谐滤波器的原理、最新研究及其在可重构光分插复用和光传输性能监测中的应用.     

A 100-Gb/s throughput ATM switch MCM with a 320-channel paralleloptical I/O interface

For an ATM switch system, we have developed a 100-Gb/s input/output (I/O) throughput optical I/O interface ATM switch multichip module (MCM) that has 320-ch optical I/O ports. This MCM is fabricated using ceramic (MCM-C) technology and very-small highly-parallel O/E and E/O optical converters. It uses 0.25-μm complementary metal oxide semiconductors (CMOS) ATM switch large scale integrations (LSIs) and has a total I/O throughput of up to 160 Gb/s. A prototype module with total I/O throughput of 100 Gb/s has been partially assembled using eight optical I/O interface blocks, each composed of a 40-ch O/E converter and a 40-ch E/O converter; the data rate per channel is from dc to 700 Mb/s. Using this module we developed an optical I/O interface ATM switch system and confirmed the operation of the optical interface     

A light-transmitting two-dimensional photodetector array using a-Sipin photodiodes and poly-Si TFT's integrated on a transparent substrate

A light-transmitting two-dimensional photodetector array (32×32 cells) using amorphous silicon (a-Si) pin photodiodes and polysilicon (poly-Si) thin film transistors (TFT's) integrated on a transparent substrate has been developed for use in a free-space optical switching network. The fabrication and the characteristics of the photodetector array are discussed. With driving circuits and sensing amplifiers, this photodetector array shows a minimum detectable power of -25 dBm and an insertion loss of 0.4 dB for an incident optical beam with a diameter of 550 μm. By monitoring the positions and the states of input optical beams, this photodetector array can be used to control the optical paths in photonic switching systems, such as a 1024-input-port optical concentrator     

Wavelength blocking filter with flexible data rates and channel spacing

This work presents a high-resolution (13.2 GHz) channel-blocking optical filter, suitable for use as a reconfigurable optical add/drop multiplexer (ROADM), which seamlessly supports data rates from 2.5 to 160 Gb/s. The filter consists of a linear array of 64 MEMS micromirrors and a high-dispersion echelle grating. The demonstrated device had an insertion loss of 9 dB, a loss ripple of 1.2 dB, and a group delay ripple of 15 ps. Data transmission through the device with various mixed data rate scenarios ranging from 2.5 to 160 Gb/s showed negligible penalty, except at 40 Gb/s where a maximum penalty of 1.5 dB was observed due to a phase coherence with the blocker filter ripple.