30.7 Tbit/s相干光PDM 16QAM OFDM 80 km SSMF传输

为了研究超高速大容量光传输系统关键技术,利用16路光源,每路光源采用相干光PDM(偏振复用)16QAM(16进制正交振幅调制)OFDM(正交频分复用)调制实现了单路传输速率为1.92Tbit/s、C波段总速率为30.7Tbit/s的80km普通单模光纤传输系统。每路光源信道包含了45路光子信道,其频谱宽度为250GHz,系统谱效率为7.68Gbit/s/Hz。所有信道经过80km传输后的误码率均低于第三代FEC(前向纠错)解码门限2×10-2。     

超100 Gbit/s光传输技术分析

介绍了超100 Gbit/s光传输所面临的主要问题及其实现的关键技术。鉴于当前光电器件工艺水平,400 Gbit/s较1 Tbit/s的光传输速率具有更高的可行性。     

超高速光通信的新技术及应用

介绍了40 Gbit/s、100 Gbit/s及以上速率超高速光通信中将会用到的新技术,包括相位调制、正交幅度调制、多电平调制等新型调制技术,偏振复用和正交频分复用等新型复用技术,相干接收技术,光子集成技术。最后介绍了这些新技术在400 Gbit/s、1 Tbit/s等超高速光通信上的应用以及超高速光通信方面的研究进展,实现了1 Tbit/s速率下CO-OFDM 1 040 km的普通单模光纤的无误码传输。     

直接检测的光正交频分复用信号光纤传输系统实验研究

研制了直接检测的光正交频分复用(OOFDM)光纤传输实验系统.实验中产生了2 Gbit/s的正交相移键控(QPSK)、正交频分复用(OFDM)光信号,并成功地在标准单模光纤中传输了200 km.测量得到在误码率为10-6时,单模光纤传输200 km后的功率代价小于2 dB.比较了光纤传输前后OFDM信号的波形、频谱以及星座图,发现光正交频分复用信号能很好地抵抗光纤中的色散效应.     

240 Gbit/s OFDM实时光通信系统的设计与实现

详细描述了240Gbit/s OFDM(正交频分复用)实时光通信系统的设计与实现。采用多载波发生装置产生3×15个相互正交的光子载波,并对每个光子载波调制4Gbaud/s速率OFDM信号,采用4QAM(二阶正交幅度调制)信号格式。在接收端,分别用对应的本征光子载波解调各路光OFDM信号,使用FPGA(现场可编程门阵列)对采样信号进行实时处理。总有效数据速率达到240Gbit/s。文章报道的传输速率为已报道实时OFDM传输的最高记录。     

超级信道在高速光标记交换系统中的应用研究

将利用光频梳产生的超级信道引入光标记交换(OLS)系统中。首先,通过仿真实现了能够产生60根可用谱线的光频梳,为光标记和超级信道提供了性能良好的光源;其次,搭建了超级信道光标记交换系统,使用正交频分复用(OFDM)的方法产生超级信道,得到携带1.25Gbit/s光标记的6Tbit/s的超级信道。仿真结果表明:在误码率为10-9时,超级信道各子信道和光标记的接收光功率分别为-5.3和-18.12dBm,实现了性能良好的高速光传输。     

超高速光通信的新技术及应用

文章介绍了40 Gbit/s、100 Gbit/s及以上速率超高速光通信中将会用到的新技术,包括相位调制、正交幅度调制、多电平调制等新型调制技术;偏振复用和正交频分复用这两种新型复用技术;相干接收技术原理、优点和应用必要性;光子集成技术的应用和技术发展。最后介绍了这些新技术在400 Gbit/和1 Tbit/s等超高速光通信上的应用。     

直调型正交频分复用多模光纤链路性能研究

正交频分复用(OFDM)技术可应用在多模光纤(MMF)通信系统中实现短距离高速信息传输.文章提出利用光学角谱法计算MMF模式色散,结合OFDM原理构建直接调制型MMF传输的理论模型,并且数值分析了传输速率和误码率(BER)等系统重要性能指标.计算结果表明,系统接收机BER为10-3时,对应同步光纤网络中的信号带宽标准OC-768(40 Gbit/s)信号,其传输距离可达2.5 km以上.     

基于训练序列的光OFDM相移估计与补偿方法

提出了单边带直接检测光正交频分复用(O-OFDM)传输系统的频域相位补偿方案.通过发送训练序列的方式,获取O-OFDM系统中信号的相位偏移随频率的变化规律,并依此对长距离传输色散影响的信号进行相位补偿.实现了单边带直接检测O-OFDM传输系统的频域相位补偿方案.仿真实验表明采用此方法40Gb/s信号在标准单模光纤中可传...     

直接检测光-OFDM系统的预失真技术研究

理论分析了直接检测光OFDM(DDO-OFDM)系统 传输链路中光电器件所导致不理想的频率响应或者功率衰减现象, 提出一种对O-OFDM信号子载波功率衰减进行预失真的技术来改善传输系统的性能。实验比 较了常规的O-OFDM信号和进行预失真 技术的O-OFDM信号在DDO-OFDM系统中传输后的性能,结果表明,在传输200km标准单模光纤(SSMF)后,常规的O-OFDM信号频 谱的高频部分有一定程度的衰减,而通过预失真技术的O-OFDM信号频谱比较平坦,且在 (BER)为10－4时,其接收灵 敏度比常规的O-OFDM信号显著地提高了3dB左右,说明使用该预失真技术可以有效地改善O -OFDM系统的性能。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

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.