Impact of polarization mode dispersion and nonlinear effect on 40 Gbit/s dense wavelength division multiplexing system

Dense wavelength division multiplexing (DWDM) system is the ultimate selection as an optical communication system because of its high speeds and capacities. However, the fiber nonlinear effects and polarization mode dispersion severely limit the performance of the system when signal propagates at 40 Gbit/s in a single channel. The coupled nonlinear Schr?dinger equations of a single channel in DWDM, which are all considered factors of group velocity dispersion (GVD), self phase modulation (SPM), cross phase modulation (XPM), four wave mixing (FWM) and polarization mode dispersion (PMD), are derived, while their number results are obtained with extended split-step Fourier method. Finally, to analyze the impacts of the fiber nonlinear effects and PMD on the optical communication system, the simulated results of an 8×40 Gbit/s DWDM system are discussed under different conditions respectively. __________ Translated from Acta Optica Sinica, 2004, 24(10): 1363–1369 (in Chinese)     

Large-Scale InP Photonic Integrated Circuits: Enabling Efficient Scaling of Optical Transport Networks

An overview of commercially available large-scale photonic integrated circuits (PICs) in indium phosphide is provided. Results of 100-Gb/s PICs that are field-deployed in wavelength-division-multiplexing (WDM) networks is provided, along with development results showing scaling of both channel count and channel bit rate to implement next-generation PICs with an aggregate capacity of 1.6 Tb/s. Use of PIC-enabled WDM systems allows affordable optical-electrical-optical (OEO) conversion and the implementation of "digital" optical networks with enhanced sub-wavelength reconfigurable bandwidth management, digital performance monitoring, and protection features. PICs will enable the continued capacity scaling required for next-generation IP core networks and support of high-bandwith 40-G and 100-GbE service connectivity between core routers     

Frequency plan and wavelength switching limits for widely tunablesemiconductor transmitters

As wavelength-division-multiplexing (WDM) channel spacing continues to decrease in size, and with the application of tunable lasers in dense wavelength-division-multiplexing (DWDM) systems, we demonstrate the ability of tunable semiconductor lasers to cope with demanding channel spacing and inevitable low frequency setting error. By finding the stable operating points of a single tunable laser at the desired frequencies, using advanced software a lookup table to drive the laser was generated. Once the drive currents to access 2000 channels with the laser are found, their frequency setting error and side mode suppression ratio (SMSR) were found. These results open up new possibilities for DWDM access networks as well as providing a limit of achievement for channel density in the network. Meanwhile, since the sampled-grating distributed Bragg reflector (SG-DBR) laser is among the most attractive sources for DWDM, it is important to investigate its wavelength switching characteristics. This behavior will affect wavelength routing and the capability limits for channel reallocation in future networks. We present new detailed experimental studies on a high-speed SG-DBR laser by using a Fabry-Perot interferometer technique adapted for the noncontinuous wave case. Measurements of fast intramodal (i.e., cavity mode) and intermodal (i.e., supermode) wavelength switching and insights into the device's dynamic behavior are obtained. Implications are given for transmitter design in dynamic wavelength routing and channel reallocation     

Modelling PBG devices to DWDM filters design

The fibre optic transmission systems require a bandwidth of about 25 THz in telecommunications networks, for which it is necessary to resort to dense wavelength division multiplexing (DWDM) systems. These systems need optical filters to broadcast selectively or not in a given wavelength band. A new very promising technology for these applications is the photonic crystals with forbidden bandgap (photonic bandgap (PBG)). In this paper, we propose a model of PBG devices to design DWDM filters on PBG materials. Copyright © 2004 John Wiley & Sons, Ltd.     

密集波分复用设备在江苏电力通信网中的应用

为解决江苏电力省市通信传输网带宽容量不足的现状,江苏电力通信采用DWDM+10 G SDH技术建设了省市主干传输网络.DWDM设备采用Alcatel 1626LM设备,采用多项先进技术,支持超长距离C波段高达192x 10 Gbit/s的网络应用.作为超大容量的传输系统在电力系统中的初次使用,DWDM设备在运行维护上要...     

Wavelength monitor integrated laser modules for 25-GHz-spacing tunable applications

Integration of 25-GHz-spacing wavelength monitors into industry standard butterfly laser modules are successfully achieved through the use of a unique optics. The 2-thermoelectric cooler (TEC) design enables independent temperature control of the laser diode and the wavelength monitor, hence eliminating the temperature dependence of the etalon as well as wavelength variation due to temperature variation and aging. As a result of the independent temperature control, narrowband tuning is easily achieved. Results from a series of thorough wavelength stability tests show that the wavelength variation of these laser modules are well within the ITU-T recommended requirement for 25-GHz channel-spacing dense wavelength-division multiplexing (DWDM) applications throughout 25 years of usage.     

Pulse generation for soliton systems using lithium niobatemodulators

We describe the principle of operation and performance of several soliton pulse sources and also a complete soliton transmitter based on lithium niobate modulators. Subsystems based on lithium niobate modulators are attractive because the modulators are now commercially available, qualified for system use, can operate up to very high speeds, and can operate over a wide wavelength range. The pulse sources we describe are based on two techniques. The first is the chirped pulse compression technique in which one or two sinusoidally driven modulators generate frequency chirped pulses that are subsequently compressed to the desired width using dispersion in a fiber. In the second technique, sinusoidally driven modulators are cascaded serially to form pulses. Using these techniques we produced nearly transform-limited pulses at repetition rates up to 15 GHz with a FWHM pulsewidths from 10-33% of the pulse period. A complete soliton transmitter using a single modulator to simultaneously generate optical pulses and encode data is also discussed. The performance of this compact transmitter in a 2.5-Gb/s soliton system experiment is comparable to other more common soliton transmitters     

A three-layer 3D silicon system using through-Si vertical opticalinterconnections and Si CMOS hybrid building blocks

We present for the first time a three-dimensional (3D) Si CMOS interconnection system consisting of three layers of optically interconnected hybrid integrated Si CMOS transceivers. The transceivers were fabricated using 0.8-μm digital Si CMOS foundry circuits and were integrated with long wavelength InP-based emitters and detectors for through-Si vertical optical interconnections. The optical transmitter operated with a digital input and optical output with operation speeds up to 155 Mb/s. The optical receiver operated with an external optical input and a digital output up to 155 Mb/s. The transceivers were stacked to form 3D through-Si vertical optical interconnections and a fabricated three layer stack demonstrated optical interconnections between the three layers with operational speed of 1 Mb/s and bit-error rate of 10^-9     

密集波分复用技术及全光网络

密集波分复用技术和全光网络已成为当前光通信的研究热点。密集波分复用技术具有超大容量、对数据信号“透明”、组网灵活等传统光纤通信技术无法比拟的优点,成为未来光纤通信的支撑技术,也成为全光网络的关键技术之一;全光网络是指对信号的传输与处理等均在光域中进行,全光网络与目前传统的通信网络相比容量更大、可扩充性和可重构性更强、网络结构更简单、对数据完全“透明”。文中对密集波分复用技术、密集分波分复用系统的构成、全光网络的概念及其网络形式进行了介绍。     

Ultra-long-haul 40-Gbit/s-based DWDM transmission using optically prefiltered CS-RZ signals

Ultra-long-haul 42.7-Gbit/s-based dense wavelength-division multiplexing (DWDM) transmission using optically prefiltered carrier-suppressed return-to-zero (CS-RZ) signal has been experimentally investigated. First, we have numerically and experimentally evaluated the impact of 3-dB bandwidth and filter detuning of bandlimiting filters on the 42.7-Gbit/s CS-RZ signal in back-to-back condition. We found that the asymmetrically filtered CS-RZ signal had a great potential for ultra-DWDM applications. Next, we have numerically and experimentally investigated the basic transmission characteristics of a 45-GHz-wide prefiltered CS-RZ signal, such as the robustness against residual dispersion, nonlinear effects, and PMD, and have confirmed that the prefiltered CS-RZ signal had less tolerance against fiber nonlinearity than an unfiltered CS-RZ signal. Finally, we have experimentally investigated the optimum filtering condition for 65- or 45-GHz-wide prefiltered CS-RZ signals in the ultra-long-haul DWDM transmission and have conducted the 70- and 50-GHz spaced 32 /spl times/ 42.7Gbit/s transmission using prefiltered CS-RZ signals. Through these experiments, we have confirmed the effectiveness of prefiltered CS-RZ signal ultra-long-haul DWDM transmission.     

Monolithically integrated eight-channel WDM modulator with narrow channel spacing and high throughput

We demonstrate an eight-channel wavelength division multiplexing (WDM) modulator module that monolithically integrates arrayed waveguide gratings and semiconductor optical amplifiers and electroabsorption optical modulators arrays. The compact module can generate individual optical signals for each WDM channel with low optical and electrical crosstalk. We show two configurations for the narrow channel spacing of 25 GHz and high throughput of beyond 80 Gb/s. Combining this WDM modulator with a multi-wavelength light source is a promising approach to creating a compact WDM optical transmitter.     

DWDM传输系统的设计与仿真

密集波分复用系统(DWDM)具有广泛应用,首先从DWDM的关键技术———掺饵光纤放大器(EDFA)进行研究,论述EDFA的噪声特征及功率谱,分析3种可能的应用及特性,在此基础上设计DWDM传输系统,分析论证设计结果.     

EA-Modulator-Based Optical Time Division Multiplexing/Demultiplexing Techniques for 160-Gb/s Optical Signal Transmission

In this paper, 160-Gb/s optical-time-division-multiplexing (OTDM) techniques employing electroabsorption (EA)-modulator-based optical multiplexer are described. The optical multiplexer integrates four EA modulators with free-space optics and enables, stably, to generate an authentic 160-Gb/s OTDM signal. The optical multiplexer possesses a switching capability of modulation format, which originates in the thermo-optic effect in EA waveguide, so that it is possible to generate various phase-coded OTDM signals such as carrier-suppressed return-to-zero (CS-RZ) signal by tuning operation temperatures of the EA modulators. By employing the novel 160-Gb/s optical multiplexer, prototypes of 160-Gb/s OTDM transmitter and receiver were developed. EA modulators are also adopted to optical short pulse source at transmitter side, optical time division demultiplexer, and phase-locked loop (PLL) circuit for clock recovery at the receiver side. The 160-Gb/s system prototype exhibited a superior performance maintaining high stability, and its applicability to practical use is discussed, showing experimental results of 160-Gb/s 635 km field trial on Japan Gigabit Network II (JGN II) optical testbed     

A Low-Power High-Speed Ultra-Wideband Pulse Radio Transmission System

We present a low-power high-speed ultra-wideband (UWB) transmitter with a wireless transmission test platform. The system is specifically designed for low-power high-speed wireless implantable biosensors. The integrated transmitter consists of a compact pulse generator and a modulator. The circuit is fabricated in the 0.5-mum silicon-on-sapphire process and occupies 420 mum times 420 mum silicon area. The transmitter is capable of generating pulses with 1-ns width and the pulse rate can be controlled between 90 MHz and 270 MHz. We built a demonstration/testing system for the transmitter. The transmitter achieves a 14-Mb/s data rate. With 50% duty cycle data, the power consumption of the chip is between 10 mW and 21 mW when the transmission distance is from 3.2 to 4 m. The core circuit size is 70 mum times 130 mum.     

福建电力DWDM环网光缆通信设计考虑

DWDM光纤系统具有带宽利用率高、扩容成本低、可传输多种格式信号、传输距离长等优点，为充分满足福建电力系统不断增长的业务要求，选择了DWDM通信系统以及环型路由结构，采用36芯G．655B和G．652B两种OPGW光缆，建设福建省调通中心至各地区电业局的光纤通信系统传输平台。文章详细地论述了DWDM系统建设中应该考虑的一系列问题。     

现代光纤通信技术的发展与趋势

该文主要论述光纤通信在当今通信领域中的重要地位及光纤通信中密集型波分复用（DWDM）的主要特点、新技术的采用、发展方向和趋势（大容量、长距离、灵活的接入方式、全光网和光交换）.目的是使人们对光纤通信的发展与趋势有进一步的了解与认识,在生产与实践中起一定的指导与参考作用.     

北电DWDM光传输系统维护浅谈

密集波分复用(DWDM)技术能充分利用光纤的巨大带宽资源,大幅度提高系统传输容量,降低传输成本,在长途传输网的超大容量传输中得到了广泛的应用.对传输维护人员来说,DWDM的应用意味着对DWDM光传输系统的维护,本文通过对北电网络的DWDM光传输系统的长期维护经验,阐述了DWDM设备的技术特点和维护方法.     

DWDM+SDH在福建电力传输网中的应用

密集波分复用（DWDM）系统具有传输距离长、容量大、波道多、实施全透明传输、能组成全光层网络和工程造价相对较低等技术经济优势。文章阐明了DWDM与同步数字系列SDH的内在关系，介绍了整个DWDM系统的组网概况，并在DWDM传输平台上配置了SDH复用保护段设备，建设福建省调通中心到各地区电业局的光纤通信系统的传输平台。     

DWDM: shaping the future communications network

This paper describes the increase in the number of optical carriers per single fiber, a technology known as wavelength division multiplexing (WDM). This successful technology takes advantage of existing glass or synthetic fiber. WDM greatly simplifies the traditional signal regeneration since optical amplification is much simpler and more cost effective than single channel amplification. However, network bandwidth elasticity is best addressed with WDM. However photonic devices performing in the low-loss spectral band have enabled more than a single wavelength in the same fiber. Thus, DWDM technology exhibits an inherent flexibility.     

DWDM传输系统工程测试

结合福建电力干线密集波分复用光传输系统的建设经验,从单机、光复用段和系统性能测试等方面,分析了DWDM传输系统工程常用的测试项目,这些常用项目的测试基本可以满足DWDM传输系统工程测试的要求。同时,介绍了测试方法和所需仪表,并提出了测试中应注意的事项。