一种新型155Mb/s大气激光通信机的研制

介绍了一种新型155Mb/s大气激光通信机的设计和试验情况.该设备采用了非球面光学系统、大功率EDFA发射、ATP跟踪等先进技术,具有通信距离远、通信速率高、工作稳定等特点.     

大气湍流对高速激光通信影响模拟实验研究

分析了大气湍流对高速激光通信影响的研究方法、现状及必要性,建立了高速激光通信用大气湍流模拟装置,提出了大气湍流对高速激光通信影响的模拟实验方案,采用实验室内半实物模拟的方法,利用大气湍流模拟装置模拟中弱强度的湍流,搭建激光传输实验系统,并进行了光强闪烁方差及频谱、到达角起伏方差及频谱等测试,结果表明,该大气湍流模拟装置的光强闪烁、到达角起伏符合-5/3理论,光强闪烁、到达角起伏是影响激光通信性能的主要因素,为深入研究大气湍流对高速激光通信影响提供了有效手段和方法,最后对大气高速激光通信未来的发展方向进行了展望。     

622 Mbit/s大气激光通信机与10/100 Mb·s-1自适应收发器的设计及集成

研制了一款用于622 Mbit/s大气激光通信机的10/100 Mb*s-1自适应以太网光纤收发器并将其集成到通信终端机模块中.该收发器以高性能的光电介质转换芯片ML6652为核心,配以必要的光收发模块和网络接口等外围器件,实现了以太网光电转换设计.从收发器主要元器件的选择、系统设计和印刷电路板设计电磁屏蔽几个方面介绍了光纤收发器的设计.整个系统具有速率高、耗能小、结构紧凑、人眼安全的特点.     

新型数据电报插入设备

本文介绍了如何利用2Mb/s码流中的通信勤务位传输数据和电报的方法.详述了数据、插入设备的设计思想、工作原理以及主要技术指标,通过该设备在邮电通信中的应用实例,阐述了该设备应用于县乡之间数据通信的重要性.     

一种大气激光通信机的总体设计

介绍了一种大气激光通信机的总体设计方案,并给出了基于该方案的试验样机的测试结果.测试结果表明:按照该方案研制的试验样机能够满足总体设计要求.     

基于低密度奇偶校验码和非对称限幅光正交频分复用技术的大气激光通信系统性能

研究了一种光功率效率高的非对称限幅光正交频分复用(OFDM)调制技术,通过对信号的非对称削减,将OFDM调制技术运用到光通信领域。将这种非对称限幅光OFDM技术运用到大气激光通信系统中,分析了采用非对称限幅光OFDM技术大气激光通信系统在大气湍流信道下的性能。在此基础上,将低密度奇偶校验(LDPC)码和置信传播迭代译码算法应用到大气激光通信系统中,并结合非对称限幅光OFDM强度调制方案,在大气湍流信道中进行了仿真。仿真结果表明,LDPC码具有优越的纠错能力并获得了较大的编码增益,该方案可以满足大气激光通信系统的需要。     

基于FPGA的空间激光通信器设计与实现

提出了一种基于FPGA的低成本、低功耗空间激光通信器实现方案。系统以FPGA为数据处理核心平台结合Verilog HDL进行软硬件设计与实现。测试结果表明,空间激光通信器在大于200m的通信距离上实现了10Mb/s的通信速率,系统具有较好的稳定性和可靠性。     

天气对大气激光通信信道的影响

大气激光通信由于其通信信道的开放性.容易受到不同天气情况的影响.本文分析了激光在大气中传输时的影响因素.并通过长期测试实验,得出不同天气类型与大气激光通信质量的关系,总结出了影响大气激光通信信道的不同天气类型.     

天气因素对大气激光通信质量影响分析

利用一套新研制的155Mb/s 5km大气激光通信机做为测试样机,进行了长达一年多的外场实验,对设备在不同气象因素条件下的工作情况进行了详细分析和理论探讨,给出了晴、阴、雨、雾、霾、大风等各种天气条件下对光通信链路的影响结果及分析.     

基于FPGA的激光通信数据模拟器

随着空间激光通信技术的发展,作为空间激光通信系统检测的必备辅助工具之一激光通信数据模拟器也开始受到人们关注。笔者基于FPGA开发平台,以FPGA为控制核心,由PC机通过RS422通信模块控制系统工作状态,采用RockI/O硬核产生1.6 Gb/s的高速激光数据,采用FPGA对数据发生器产生的数据进行CRC编码和8B/10B编码,经过并串转换后模拟输出100 Mb/s的中速激光数据,最后采用光电转换模块将其转换为激光信号在空间传播,激光通信接收端经过光电转换,串并转换等数据处理,同时将接收数据转发给PC机进行存储分析,完成激光通信的测试。     

光网络中的动态可重构的光分插复用技术

动态可重构的光分插复用器(ROADM)在光通信网络与传感网络中有重要的应用,而且是对目前正在使用的非重构的光网络升级的核心技术之一.超大规模、高可靠性的传感器网络对可重构的OADM需求尤其迫切.结合本课题组承担的863项目的研究成果,对该技术进行介绍.     

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.     

Calibration of optical modulators by optical down-conversion

A new method for the calibration of intensity modulators and modulated laser diodes at millimeter-wave frequencies is presented. The method uses an integrated-optic modulator as both a mixer and a frequency doubler. To demonstrate the measurement technique an intensity modulator is calibrated over the band 26.5-40 GHz. The measurement system employs no components exceeding 20 GHz (excluding the RF generator), and with relatively minor modifications measurements in excess of 60 GHz are feasible     

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.     

Coherent optical tapping using semiconductor optical amplifier

Semiconductor optical amplifiers are attractive not only as optical repeaters but also as functional devices, since carrier density modulation in amplifiers causes a nonlinear phenomenon. Utilizing the effect of the carrier density modulation on the semiconductor optical amplifier junction voltage, a coherent optical tapping is proposed for signal monitoring or control signal extraction. A 155 Mb/s FSK (frequency shift keying) signal tapping was realized with a simple configuration using heterodyne single-filter detection with -24.4 dBm sensitivity. Many applications for this coherent optical tapping are discussed, and basic characteristics for frequency-selective tapping from FDM (frequency division multiplexing) signals and optical amplifier gain control are examined     

利用光学微分预处理的强度光学相关

本文把采用菲涅耳全息滤波器的强度光学相关识别系统与光学微分预处理系统相结合,通过对输入图像进行边缘增强预处理,强度相关器的鉴别能力得到了改善。给出了理论分析和实验演示的结果。     

Nonlinear optical glasses for ultrafast optical switches

In this paper we report degenerate four-wave-mixing measurements of the nonlinear coefficient of rutile and a number of optical glasses at 1.06 μm. We define a figure of merit which measures the suitability of a material for nonlinear waveguide switches and show that the best glasses have figures of merit substantially higher than any other material. We include a brief discussion of the types of switching elements that could be made with these materials.     

全光通信中的光开关技术

光开关是实现全光交换的核心器件,光开关的研究已成为全光通信领域研究的焦点。本文首先对光开关的原理进行归纳,总结光开关的应用范围。对传统机械式光开关、微电子机械式光开关、热光开关进行了进一步地划分,分析了它们的结构形式和性能特点。设计了光开关性能评价指标体系,对常见的4种光开关进行了定性与定量对比,指出不同类型光开关的优点和不足之处。最后依据全光通信网的发展趋势,指出大容量、高速、透明、低损耗是光开关的重点发展方向。     

High-speed optical FSK modulator for optical packet labeling

We described a novel optical label swapping (OLS) technique for optical packet systems using frequency-shift-keying (FSK) optical labeling. High-speed optical FSK signal can be generated by using an external FSK modulator consisting of four optical phase modulators. The FSK modulator was based on optical single-sideband (SSB) modulation technique, and comprised of traveling-wave electrodes for high-speed frequency switching. We demonstrate 10 Gbps FSK transmission, and simultaneous modulation by FSK and intensity modulation (IM). OLS using double-sideband modulation was also demonstrated, where this technique can be used for a bundled wavelength-domain-multiplexing (WDM) channels without using an array of pumping light sources.     

光交叉连接器的光传输中的应用

目前以IP业务为代表的数据业务爆炸式增长,单信道传送速率从2.5Gb/s到10Gb/s到40Gb/s的快速增长,密集波分复用技术的使用,骨干网的电信级大容量快速交换需求,使得对光传送网交换节点的要求越来越高.网络的生存性、网络的恢复和自愈问题都变得非常重要.光交叉连接器(OXC)技术的发展,替代了复杂昂贵的电交叉连接,使空闲光纤数减少.同时,不需要光电转换,提供了比电交叉连接更高的交换效率.OXC能在光层解决网络恢复和自愈问题,极大地提高了网络的生存性和恢复速度.因此,光交叉连接器作为光传送网的关键设备,它的发展将对光传送网起到重大的推动作用.