基于GPON业务的FSO传输系统

主要探讨了3G网络时代下基于GPON业务的无线激光传输设备(FSO)的经济性,比较分析了GPON 业务在FSO系统中传输的技术优势.重点描述了突发式通信机制如何联合FSO设备实现通信传输,并对其实现方案进行了阐述.     

基于FSO系统的多进制LT码性能分析

为克服空间光通信(FSO)链路受大气湍流效应的影响,将LT码应用到FSO系统中.多进制LT码具有较高的传输效率.提出一种新型度分布函数来改善多进制LT码的译码性能.计算不同进制LT码的译码失败率,并模拟强湍流信道,对采用不同编码方案的FSO性能进行仿真.结果表明:采用新型度分布的LT码能够降低译码失败率,且能有效改善FSO系统在强湍流情况下的性能.     

FSO通信系统中振动的影响

在FSO通信系统中，装置平台的振动对FSO通信系统的误码率有很大的影响，而误码率又直接决定了FSO系统的通信质量。本分析了当发射光束为高斯光束时，振动对FSO系统误码率的影响。研究发现，装置平台振动的振幅、FSO系统的通信距离对误码率的影响相当大，FSO系统所选用的波长对误码率基本上无影响。     

寒温带气候下FSO系统传输试验分析

分析了自由空间光通信(FSO,Free Space Optica Communication)系统在应用中受气象条件影响的因素.试验通过对哈尔滨市区内的一对试验FSO通信系统在各种气象条件下传输性能的的跟踪测试,以极限恶劣天气(沙尘暴、大雪低温)为例,对FSO系统在黑龙江省的寒温带气候特征下应用时的传输性能作了试验分析,并得出了相关结论及解决办法.     

自由空间光通信技术的应用与发展

自由空间光通信(FSO)是小功率红外激光束以大气为介质传送光信号的一种激光通信系统.文章简要介绍了国内外FSO技术的发展现状,简述了FSO是现阶段解决"最后一公里"瓶颈问题的有效途径,特别强调了FSO系统在解决宽带网络"最后一公里"瓶颈的重要作用和意义.     

FSO关键技术及应用

文章从自由空间光通信(FSO)的概念和原理出发,重点研究了FSO系统的几个关键技术:冗余链路控制技术、动态跟踪控制技术、FSO网管和FSO网络安全,并简单探讨了它在光通信接入中的广泛应用.     

全双工逆向调制自由空间激光通信系统的设计与分析

逆向调制自由空间激光通信(MRR FSO)系统是将传统FSO链路的一个终端替换成逆向调制器(MRR)而构成的一个非对称FSO系统,因其功耗低、MRR端体积小和易安装等优点,成为自由空间光通信技术研究热点之一。针对MRR FSO系统现存在的捕获系统复杂、对准难度大等技术难题,在原有MRR FSO系统的基础上设计了一种全双工MRR FSO系统。其中光收发机端的共用光学天线模块采用较大孔径的反射式天文望远镜系统,主要用来减小光束发散角、增加接收孔径。MRR端采用单个大尺寸或多个小尺寸MRR器件,来提升反射光信号质量,并搭建室外长距离实验系统,对该MRR FSO系统进行测试,验证了该系统的合理性。结果表明,所设计的全双工MRR FSO系统在长距离全双工激光通信是可行的,为最终实现长距离全双工MRR FSO系统做铺垫,是未来MRR FSO技术的发展方向之一。     

基于LDPC编码的双工逆向调制自由空间光通信系统

在逆向调制(modulating retro-reflector,MR R)自由空间光通信(free-space optical,FSO)系统中, 激光信号在传输过程中受到双程大气湍流的严重影响,导致系统误码率性能恶化。本文提出 采用低密度奇 偶校验编码(low density parity check,LDPC)方法来降低MRR FSO通信系统的误码率, 并且尝试使用微角 锥棱镜阵列(microcorner cube retroreflector arrays,MCCRA)来改善MRR FSO信道的传 输稳定性。本项研究 中搭建了MRR FSO通信实验平台,进行了基于LDPC编码的频分双工MRR FSO通信实验。实验结 果表明 使用LDPC编码的MRR FSO系统增益约为3dB,使用微角锥棱镜阵列作为MRR FSO反射器件能够 通过补 偿大气湍流引起的相位畸变来提升系统性能。结果还证明了LDPC编码相较于MCCRA,更能够 提升MRR FSO系统的误码率性能。由此可见,将LDPC编码方式与微角锥棱镜阵列结合运用于MRR FSO系 统能获得更加优化的系统性能。     

基于2×2放大转发中继的混合RF/FSO系统性能分析

基于放大转发中继方式,研究了2×2中继条件下混合RF/FSO航空通信系统性能。FSO链路服从适于孔径平均条件下的Exponentiated Weibull大气湍流分布模型,RF通信链路为Nakagami-m衰落信道。建立2×2中继混合RF/FSO通信系统模型,利用Meijers’G函数推导求出航空激光通信系统信噪比的概率分布函数及累积分布函数,进一步推导混合通信系统平均误码率和中断概率的闭合表达式。通过仿真分析了不同大气湍流强度、孔径尺寸和调制方式对平均误码率和误码率的影响。仿真结果表明,混合系统中断概率及误码率受湍流强度影响较大,孔径平均效应可有效改善混合RF/FSO传输系统的性能;固定增益中继方式下,混合RF/FSO系统性能主要由RF链路决定;在固定增益中继混合RF/FSO系统中起主要作用;可变增益中继混合RF/FSO系统中,具有较小信噪比的链路在对系统性能的影响起主要作用。     

FSO系统在下一代移动承载网中的应用

本文简要描述了移动承载网的演进趋势及自由空间光通信（FSO）系统的关键技术。在此基础上,分析了在下一代移动承载网中FSO承担的角色。重点讨论了在下一代移动回传网中FSO的应用。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Technology innovation and process integrations for sub-100nm gate patterning

This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

Complete approach to automatic identification and subpixel center location for ellipse feature

To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.     

小角度扩展相关性近似算法分析

本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.