Low-noise optical receiver for high-speed optical transmission

This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlingtou circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitivity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10^-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.     

Low-noise optical receiver for high-speed optical transmission

This paper describes the design of a low-noise optical receiver using Si bipolar transistors for high-speed optical transmission. The conventional common emitter-common collector circuit (CE-CC pair) and Darlington circuit (transimpedance amplifiers with parallel feedback) are studied. Optimal CE-CC pair collector-biasing current for attaining minimum noise current with a 400-MHz bandwidth is 2.7 mA, and less than 1.2 mA for the Darlington circuit. It is confirmed that the Darlington circuit is better than the CE-CC pair in signal-to-noise ratio by about 1.5 dB. The low-noise Darlington optical receiver with a Ge-avalanche photodiode has achieved an optical sensitiyity of -41 dBm for a 400 Mbit/s RZ pulse with a bit error rate of 10^-10. This is a 2.5-dB improvement in optical sensitivity over that of the conventional CE-CC receiver.     

Modeling high-speed optical transmission systems

Computer simulation of a 2.5-Gb/s intensity-modulated/direct-detected optical system with high path dispersion is described. This simulation, based on single-mode laser diode rate equations, includes transmit and receiver circuit filtering, receiver circuit noise, avalanche photodiode noise, fiber dispersion, and laser chirp. The rate equations are sufficiently general to model mode-offset distributed feedback laser diodes. The system power penalty, due to laser chirp and fiber dispersion, is calculated using Gaussian quadrature numerical integration. By simulating a population of some 12800 laser diodes and correlating the performance of each laser in a transmission system with its spectral characteristics, it is possible to deduce laser specifications that will assure satisfactory operation in long-span links. These results are used to study a laser diode specification under consideration by CCITT, and, by studying the simulated laser line shapes, some modifications to the CCITT specification are considered     

用于高速光电组件的光焊球阵列封装技术

本文介绍了用于高速光电组件的表面安装型焊球阵列(BGA)封装技术。     

低功耗DDR高速信号的封装布线方案设计及信号完整性分析

不同于印制电路板的制作工艺,芯片封装基板的走线更细,线间距更窄。狭小的布线空间使传输线效应更为明显,而且封装设计的好坏直接影响芯片是否可以正常工作,同时芯片成本的控制要求布线层尽量要最少。这些问题使得高速信号布线面临严峻的挑战。在国家科技重大专项的资助下,使用全波电磁场仿真工具进行建模分析,研究了布线中线宽、线间距和参考地对信号传输质量和信号间串扰的影响,并且基于一款低功耗DDR高速芯片的双层封装布线设计,在实际设计方案中对分析结果进行了仿真验证,最终得到了一种高质量、低成本封装基板高速布线方案,速率达到1 333 Mb/s。     

Subcarrier multiplexing for high-speed optical transmission

The performance of high-speed digital fiber-optic transmission using subcarrier multiplexing (SCM) is investigated both analytically and numerically. In order to reduce the impact of fiber chromatic dispersion and increase bandwidth efficiency, optical single-sideband (OSSB) modulation was used. Because frequency spacing between adjacent subcarriers can be much narrower than in a conventional DWDM system, nonlinear crosstalk must be considered. Although chromatic dispersion is not a limiting factor in SCM systems because the data rate at each subcarrier is low, polarization mode dispersion (PMD) has a big impact on the system performance if radiofrequency (RE) phase detection is used in the receiver. In order to optimize the system performance, tradeoffs must be made between data rate per subcarrier, levels of modulation, channel spacing between subcarriers, optical power, and modulation indexes. A 10-Gb/s SCM test bed has been set up in which 4 × 2.5 Gb/s data streams are combined into one wavelength that occupies a 20-GHz optical bandwidth. OSSB modulation is used in the experiment. The measured results agree well with the analytical prediction     

A high-speed GaAs MESFET optical controller

Optical interconnects are being considered for control signal distribution in phased array antennas. A packaged hybrid GaAs optical controller with a 1:16 demultiplexed output that is suitable for this application is described. The controller, which was fabricated using enhancement/depletion mode MESFET technology, operates at demultiplexer-limited input data rates up to 305 Mb/s and requires less than 200 μW optical input power     

Recent progress on high-speed optical transmission

The recently reported high spectral efficiency (SE) and high-baud-rate signal transmission are all based on digital coherent optical communications and digital signal processing (DSP). DSP simplifies the reception of advanced modulation formats and also enables the major electrical and optical impairments to be processed and compensated in the digital domain, at the transmitter or receiver side. In this paper, we summarize the research progress on high-speed signal generation and detection and also show the progress on DSP for high-speed signal detection. We also report the latest progress on multi-core and multi-mode multiplexing.     

高空高速环境热光学分析及光学窗口设计

为提高高空高速环境下机载光谱相机光学系统的成像性能,分析了飞行高度对光学窗口面型变形的影响,合理设计光学窗口厚度。基于有限元流固耦合、流热耦合模型,仿真高空高速环境下气动压力、气动热载荷对光学窗口的作用,分析了飞行高度对不同厚度光学窗口面型变形的影响;初步选择光学窗口厚度,利用Zernike多项式对该光窗面型变形进行拟合并输入光学软件,以MTF及波相差为评价指标,分析了光学窗口变形对光学系统成像性能的影响,最终确定合理的光学窗口厚度。结果表明:飞行器在5～30 km高空以3 Ma速度、5毅攻角飞行时,口径200 mm的光学窗口合理设计厚度为15 mm。为不同飞行高度范围光学窗口厚度的选择及优化提供了一定依据。     

高速光交换机竞争调度策略

在光交换网络中,当同一波长两个或多个光分组同时离开光交换机的同一个输出端口时将会发生对输出端资源的竞争,竞争失败的光分组将受阻,如何有效地调度将使光交换系统性能受到很大影响,文章综述了目前解决光交换网分组冲突的几种方案,阐述了各种解决方法的原理、实现方式及特点,展望了今后可能采用的最佳竞争调度方案.     

A proposed new high-speed optical detector

The small-signal optical detection properties of the barrier injection transit-time (BARITT) diode structure are presented. At low frequencies, the device behaves as a punch-through phototransistor while at frequencies near the transit-time frequency the device is capable of additional gain due to negative-resistance reflection-type amplification.     

Packaging and integration technologies for future high-frequency power supplies

This paper reviews data from the International Technology Roadmap for Semiconductors to establish where dc-dc converters are headed in the first decade of the new millennium. It focuses on the high performance computing (high current, fast response, high power density) and portable/handheld (low profile) sectors. Magnetics and power device packaging technologies needed to allow power supplies to move to operating frequencies in the 1-10 MHz region are discussed. It introduces the concept of magnetic components fully embedded (windings and core) in PCB and silicon offering low profile and low losses at high frequency. It also reviews developments in wirebond-free power packaging such as flip-chip assembly that offer low profile, reduced parasitics and increased thermal performance. Finally, consideration is given to the changes in the power electronics industry that may need to be addressed to enable these new technologies to play a strategic role.     

Architectures and technologies for high-speed optical data networks

Current optical networks are migrating to wavelength division multiplexing (WDM)-based fiber transport between traditional electronic multiplexers/demultiplexers, routers, and switches. Passive optical add-drop WDM networks have emerged but an optical data network that makes full use of the technologies of dynamic optical routing and switching exists only in experimental test-beds. This paper discusses architecture and technology issues for the design of high performance optical data networks with two classes of technologies, WDM and time division multiplexing (TDM). The WDM network architecture presented stresses WDM aware Internet protocol (IP), taking full advantage of optical reconfiguration, optical protection and restoration, traffic grooming to minimize electronics costs, and optical flow-switching for large transactions. Special attention is paid to the access network where innovative approaches to architecture may have a significant cost benefit. In the more distant future, ultrahigh-speed optical TDM networks, operating at single stream data rates of 100 Gb/s, may offer unique advantages over WDM networks. These advantages may include the ability to provide integrated services to high-end users, multiple quality-of-service (QoS) levels, and truly flexible bandwidth-on-demand. The paper gives an overview of an ultrahigh-speed TDM network architecture and describes recent key technology developments such as high-speed sources, switches, buffers, and rate converters     

Single-side-band optical modulation in SCM systems for high-speed optical transmission

In order to decrease dispersion penalty and increase the optical bandwidth efficiency,an optical single-side-band modulation(SSBM) scheme in sub-carrier multiplexing(SCM) is proposed.The principle of the SSBM is analytically presented,and a configuration for generating optical SSB signal is proposed using a balanced Mach-Zehnder electro-optic modulator.     

高速光纤系统中光双二进制传输性能分析

研究了光双二进制调制格式的传输性能,分析了光双二进制调制格式的不同实现形式及其对应的时频特性,并进行了仿真。在此基础上,讨论了采用低通滤波器实现光双二进制调制格式时滤波器带宽对调制码型的影响。     

高速光学模数转换器的研究现状及进展

高速高精度模数转换器（Analog-to-digital Converters,ADC）是现代数字信息处理系统中的关键组成部分,现有的电子模数转换器存在运行速率严重受限的难题,因此引入光学方法实现高速高精度模数转换成为研究的热点。本文重点针对高速光学模数转换器的研究现状及进展进行了探讨,并对光学辅助、光采样电量化、电采样光量化以及全光采样量化目前4种最主要的光学模数转换器的原理、结构和最新的研究进展进行了详细的介绍。     

InP-based integrated optical components

The possibilities of fabricating integrated optical components on an InP substrate are demonstrated by a number of devices that have been made in recent years. These components can have a major impact on evolving communication networks by facilitating new techniques for increasing capacity such as wavelength division multiplexing and soliton transmission.     

Three-dimensional high-frequency distribution networks. II.Packaging and integration

This paper describes the implementation and packaging of the components, described in Part I of this paper, to realize a three-dimensional W-band distribution network     

Packet optical networks for high-speed TCP-IP backbones

This article presents a new proposal for TCP-IP backbone implementation based on optical packet switching technology. The proposed network architecture merges the flexibility in resource management of packet switching with the high capacity offered by full optical technology