空心Kagome光子晶体光纤中等离子诱导产生的色散波

通过在充氪(Kr)气体的空心Kagome光子晶体光纤中输入超短脉冲,产生中红外波段的色散波,并利用单向脉冲传输方程对色散波进行数值模拟和分析。主要探讨了两种输入脉冲:中心波长为1.4μm的高斯型脉冲和在此基础上加入其双倍频叠加而产生的双色近锯齿波脉冲。两种情况下均产生了多个色散波,并符合相位匹配条件。为优化色散波,将近锯齿波作为抽运光。当充入光纤的Kr气体因抽运光压缩而二次电离时,已产生的色散波发生转换,变为新的更长波长的色散波。这种色散波现象可以通过等离子体修正的相位匹配条件来解释。深入探讨了中红外波段超短脉冲的产生机制以及色散波理论。     

基于正常色散硫系波导的宽可调谐中红外频谱转换

中红外-近红外频谱转换是实现诸多中红外波段应用的重要技术,转换效率和调谐范围通常由于泵浦-信号频率失谐量大而受限.提出一种新型As2Se3硫系光波导,通过色散调控对波导结构进行优化设计,使光波导在2 μm波长附近具有正常群速度色散及负的四阶色散,达到泵浦-信号频率失谐量大的四波混频过程的相位匹配.研究了该波导的中红外-...     

光纤色散效应对脉冲展宽的影响

为了研究光通信系统中光纤色散特性对通信系统传输性能的影响,基于单模光纤和多模光纤的色散特性,采用数值模拟计算的方法,对脉冲展宽、光纤内部的偏振模色散、色度色散、波导色散和模间色散的物理机制进行了分析,分别得到了折射率n=1.516和n=1.458的标准单模光纤经过10km传输距离后色散导致脉冲展宽的结果,比较了传输波长在850nm和1310nm时多模光纤的色散效应,通过对不同光源LD(Δλ=1nm)和LED(Δλ=70nm)的比较,分析了光谱宽度对脉冲展宽的影响。结果表明,纯石英光纤在系统传输波长为1.27μm处群速度色散等于0;折射率渐变多模光纤工作在常见的850nm以及1310nm通信窗口时,其模内色散表现为负色散;色度色散和模间色散引起的脉冲展宽随光纤的数值孔径、材料折射率和光源光谱线宽的增大而增大。     

太赫兹波在砷化镓波导中的产生与传输

为提高太赫兹(THz)波的产生效率,研究了飞秒激光与GaAs 晶体的相互作用。首先研究了块状GaAs 晶体中泵浦光与THz 波间的相位匹配,结果显示泵浦光的群折射率曲线与THz 波的折射率曲线不存在交点,表明了块状晶体结构中相位失配问题的存在;然后设计了四种不同尺寸的波导结构,根据波导理论计算了波导结构在0.1~6 THz 波段的折射率,并结合波导的吸收和色散参数分析了THz 波在晶体中的最佳传输距离。研究结果表明,GaAs 波导结构能够有效增大泵浦光与THz 波的相位匹配程度,从而提高飞秒激光与晶体耦合过程中THz 波的产生效率。研究为基于飞秒激光与GaAs晶体相互作用的高效THz 产生技术提供了理论依据。     

QPSK信号下富碳化硅双slot波导的相位敏感放大特性研究

相位敏感放大可以改善光通信传输链路的传输性能,是全光信号处理领域中的重要组成部分。本文通过结合一种碳硅原子比为1.28的富碳化硅,构建了水平双slot结构的硅基波导模型。该模型的色散平坦部分覆盖500 nm左右的波段且具有多个零色散点,非线性系数最高可达20000 W^-1·m^-1。通过采用有限元法分析计算其在通信波段的模场分布、色散特性及非线性特性。同时结合结构尺寸优化后的波导模型,建立了在硅基波导中基于四波混频效应的光传输模型,并求解分析了该波导在QPSK信号下的相位敏感特性。仿真结果表明该波导可以实现34 dB相敏增益,在片上信号处理领域具有潜在的应用前景。     

啁啾光纤光栅在硫系光纤激光器中的色散补偿

中红外波段包含极其重要的大气窗口和众多分子的指纹区,基于硫系玻璃的中红外光纤激光器逐渐引起人们的重视。由于硫系玻璃具有极高的非线性和色散特性,脉冲激光在硫系光纤中的展宽成为发展中红外超短激光必须解决的重要问题。针对脉冲激光在硫系光纤中传输的展宽问题,设计线性啁啾光纤光栅,用于补偿高斯脉冲激光经过光纤之后的色散展宽。模拟结果表明:光纤色散导致的脉冲展宽可以通过线性啁啾光纤光栅进行很好的补偿。进一步研究发现,通过对设计的啁啾光纤光栅运用高斯变迹函数进行切趾优化,可以显著改善色散补偿的效果,以获得对脉冲激光色散展宽的完全补偿。文中的研究对于设计高质量的硫系中红外光纤激光器具有理论指导意义。     

利用光脉冲传输特性抑制偏振模色散

基于双折射光纤中光脉冲传输方程,详细分析了二阶色散、自相位调制以及交叉相位调制在光脉冲传输过程中引起的啁啾。分析结果显示:通过合理选取入射功率,二阶色散引起的啁啾与自相位调制引起的啁啾在脉冲中心附近可以相互抵消,从而使脉冲展宽最小;交叉相位调制产生的两偏振分量的啁啾引起的频移,可使两偏振分量间产生互束缚,利用这种现象可以抑制偏振模色散。     

色散光纤中超连续谱的产生及多波长输出

超短脉冲在高非线性光纤中传输过程遵循非线性薛定谔方程,因此可通过分步傅里叶变换的方法对此过程进行数理模拟和分析。借用MATLAB工具软件产生一个高斯皮秒脉冲,研究脉冲通过色散光纤之后频谱得以展宽,从而能够通过阵列波导光栅(AWG)进行分波之后得到多波长输出的超连续谱。结果表明:使超连续谱频谱得以展宽的因素有很多,其中群速度色散值对其影响较为显著。对光纤及脉冲的各参数进行优化调节之后,再对色散参量D0进行微调,超连续谱将得到更好地修整优化,频谱变得更宽且平坦稳定。     

初始啁啾对高斯脉冲形成光孤子的影响

本文通过解薛定谔方程分别研究了线性光纤中色散导致具有初始频率啁啾的高斯脉冲展宽的详细物理过程和非线性光纤中自相位调制导致光脉冲频谱展宽的详细物理过程 ,得到高斯脉冲在光纤中群速度色散所导致的频率啁啾在反常色散区是下啁啾 (负啁啾 ) ,与脉宽的关系是线性的 ,自相位调制所产生的频率啁啾是上啁啾 (正啁啾 ) ,在脉冲的中心部分近似为线性 ,当CPβ2 <0时 ,脉冲有一个初始窄化的阶段等结论。最后用计算机模拟光孤子传输估算出形成孤子的初始啁啾范围值。     

利用光脉冲传输特性抑制偏振模色散

基于双折射光纤中光脉冲传输方程，详细分析了二阶色散、自相位调制以及交叉相位调制在光脉冲传输过程中引起的啁啾。分析结果显示：通过合理选取入射功率，二阶色散引起的啁啾与自相位调制引起的啁啾在脉冲中心附近可以相互抵消，从而使脉冲展宽最小；交叉相位调制产生的两偏振分量的啁啾引起的频移，可使两偏振分量间产生互束缚，利用这种现象可以抑制偏振模色散。     

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.     

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.     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

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.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks