简并的四波混频后向波参量振荡

普通的简并的四波混频作用都是获得后向波参量放大作用,即有一定强度的物波输入,观察此物波的位相复共轭的后向反射波,后向反射波与物波强度之比称为非线性反射率,对于参量放大作用,此非线性反射率小于1。本文报道了在共线和非共线抽运情况下,用硝基苯作非线性介质,观察到简并的四波混频后向波参量振荡作用,即在没有物波输入时,由于自发发射的放大而产生的后向波参量振荡作     

钠蒸气近4D能级双光子共振光谱分析

由钠蒸气近4D能级双光子共振光谱证实，存在330nm纯参量四波混频信号，共振时参量四波混频抑制了放大的自发辐射，而激光波长失谐时产生的受激超拉曼散射削弱了参量四波混频。     

瑞利增强和布里渊增强四波混频的研究

瑞利增强和布里渊增强四波混频的研究姜谦，俞祖和，米辛，李晓峰，傅盘铭（中国科学院物理研究所，北京１０００８０）拉曼增强非简并四波混频可以克服ＣＡＲＳ存在的空间分辨率不高及ＲＩＫＥＳ存在的对检偏元件要求高等缺点。本工作中，我们用拉曼增强非简并回波混频方...     

光纤中非线性参量过程

在受激散射过程中,光纤作为非线性介质,通过分子振动或声子的参与而起主动作用.然而在其它许多非线性现象中,光纤仅起被动作用,几个光波之间通过束缚电子的非线性响应产生相互作用。因为这些过程由光对介质参量(如折射率)感应调制所致,所以人们把它们统称为参量过程.这类过程包括谐波产生、四波混频、参量放大等非线性现象。本文§1节讨论四波混频的起因,§2节讨论四波混频理论,重点在参量增益。§3节介绍相位匹配技术和实验结果。§4节讨论参量放大及其应用。最后,§5节集中研究和频以及谐波的产生,并着重讨论了光纤中的二次谐波产生.当光纤以特定方式预置时,出现了出乎意外高的二次谐波转换效率。     

一种研究Rydberg原子的新方法:非简并四波混频方法

众所周知,非简并回波混频可被用于高分辨率激光光谱学,以研究原子或分子能级结构和弛豫过程．我们曾用时间延迟Ｒａｍａｎ增强非简并四波混频光谱学方法测量振动的失相时间,尤其是将双频非简并四波混频方法用于超快调制光谱学,等等．Ｒｙｄｂｅｒｇ原子是原子物理学中的重要研究领域．在本论文中,我们首次将非简并四波混频方法推广到Ｒｙｄｂｅｒｇ态系列的研究．这种方法的主要特点是：它是非线性光学方法,信号为相干光,探测灵敏度高． 虽然人们对钠原子Ｒｙｄｂｅｒｇ态系列已进行了许多研究,但用非简并四波混频方法来研究用原子…     

利用四波混频消除图像畸变的局限性

一、引言 在大多数理论研究中,人们仅在平面泵浦和探测波的条件下研究四波混频产生位相共扼波的机理、手段。然而在实际应用简并四波混频共轭波补偿大气干扰时,入射到位相共轭镜上的探测波不可能是理想平面波。但是在大多用相位共轭消畸变的方案中都忽略了畸变探测波在简并四波混频中产生什么样的“共轭波”这个问题。本文将讨论利用简并四波混频消除通过湍流大气传输图像的畸变问题。     

钠蒸气参量四波混频紫外辐射的产生

记录并分析了钠原子蒸气形成近４Ｄ能级双光子共振参量四波混频产生的３３０ｎｍ信号，描述了信号强度随实验条件变化的规律，确定了最强辐射条件。     

波前畸变的弱激光参与的简并四波混频的理论研究

针对四波混频技术在军事上的应用，计算了经过大气畸变的弱激光参与的简并四波混频过程，得到了共轭反射率的表示式，讨论了反射光与信号光近似100％共轭所需的条件。     

钡蒸气中放大自发辐射与参量四波混频的竞争

研究了在双光子共振条件下，Ｂａ蒸气中放大自发辐射（ＡＳＥ）与参量四波混频（ＰＦＷＭ）的竞争过程，其机制可归结为ＡＳＥ与ＰＦＷＭ之间的干涉相消。     

在有机染料溶液中简并的四波混频

R. M. Hellwarth、A. Yariv和D. M. Pepper、D. M. Bloom和G. C. Biorklund在1977年几乎同时提出简并的非线性四波混频的概念,这引起人们很大的兴趣。用这种简并的四波混频过程可以得到原始波的位相复共轭波。因此,这在信息处理中有很大的意义,并且用这种方法可以获得高质量波面的反射放大器和振荡器。     

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