Compton散射下强激光等离子体的辐射阻尼效应

为了研究Compton散射对强激光等离子体中辐射阻尼效应的影响,采用多光子非线性Compton散射模型、相对论理论和洛伦兹变换方法,对Compton散射对不同极化激光在等离子体中产生辐射阻尼效应的影响进行了理论分析和数值计算。提出了将Compton散射光作为等离子体产生辐射阻尼效应的新机制,给出了辐射阻尼满足的修正方程。结果表明,Compton散射使等离子体辐射阻尼效应对电子运动产生重要作用的几率增大,这主要是由于产生这种作用所需的入射激光强度降低,从而使电子频率增大、电场耦合频率增大的缘故。多光子非线性Compton散射光是产生和提高等离子体辐射阻尼效应的一个重要机制。     

激光功率密度对自生磁场和电子热传导的影响

为了理解超强激光与等离子体相互作用中产生的自生磁场形成机制和电子热传导特性,采用相对论电磁粒子模拟程序,估算了不同激光功率密度下,在等离子体表面所形成的电磁不稳定性产生的自生磁场大小和空间分布,得到了超热电子和经典Spitzer-Harm理论描述的电子热流随激光功率密度的演化情形.结果表明,非Maxwell速度分布的等离子体,由于电子初始时刻的无规则热运动,在等离子体上激发电磁不稳定性,而不稳定性激发的强电磁场使电子束在非常短的距离内沉积能量,同时对在激光有质动力推开电子时形成的超热电子能量输运产生抑制作用.这一研究结果对更好理解惯性约束核聚变快点火过程中自生磁场的产生、电子热传导等方面有帮助的.     

激光等离子体相互作用中的自生磁场和超热电子热输运

应用相对论电磁粒子模拟程序,研究了线性极化强激光入射到无碰撞密度均匀等离子体时被加速的超热电子及电磁不稳定性机制。讨论了电磁不稳定性激发的自生磁场和超热电子热传导特性。 用Spitzer-Harm理论分析了电子热传导中能量的运输情况,观察到由激光的非等方加热引起的电子纵向加热现象。结果表明,不稳定性激发的强电磁场使电子束在1 μm的距离内沉积能量,同时对在激光有质动力推开电子时形成的电子热流产生抑制作用。     

强激光等离子体中质子加速的新机制

为了研究等离子体中Compton散射对靶背法向方向加速质子的影响,采用多光子非线性Compton散射模型和等离子体模拟方法,对Compton散射下等离子体中的质子加速进行了理论分析和数值模拟,提出了将入射光和Compton散射光作为在等离子体靶表面处形成的静电场加速质子的新机制,得到了质子加速的一些重要数据。结果表明,Compton散射使等离子体内产生的高能电子数增加,高能电子靶表面上所产生的静电场增强,从而使质子获得更高的加速能量;散射使静电场增强效应,有效地补偿了因激光调制不稳定性增强而造成电子在向等离子体输运过程中的能量损失,从而使质子从平缓密度标长等离子体中获得的加速能量高于从陡峭密度标长等离子体中获得的加速能量。因此,采用Compton散射下的平缓密度标长等离子体加速质子较为理想。     

超强激光与等离子体相互作用中的自生磁场及三维模拟

用3维粒子模拟程序对超热电子在等离子体靶表面中向前传输时所激发的电流密度,电场和磁场的发展过程进行模拟研究。数值模拟表明,在线性强激光作用下,由于电子初始时刻的无规则热运动,在等离子体临界表面上激发不稳定性,而不稳定性随时间发展和激光功率的进一步深入到等离子体内部,最终使等离子体表面处激发饱和自生磁场,饱和自生磁场对激光有质动力推开电子时所形成的高能电子运动产生抑制作用.通过该研究寻找相对论效应条件下的自生磁场,并为进一步开拓其在高能离子束的应用提供理论和技术上的指导。     

Compton散射下等离子体初温对质子产生的影响

应用多光子非线性Compton散射模型和二维particle-in-cell(PIC)粒子模拟程序,研究了Compton散射下等离子体初始温度对质子产生的影响,并进行了数值模拟。结果表明:与Compton散射前相比,随着等离子体初始温度的增加,产生的质子数有更显著的增加,靶前和靶后质子能谱曲线趋于平滑,加速质子数量的差别减小。当入射激光强度增强时,随着等离子体初始温度的增加,质子增加的相对幅度有明显减小。当入射激光强度减弱时,随着等离子体初始温度的增加,质子能谱曲线仍有清晰的区别,质子数量和速度都有明显的增加。     

Compton散射下正弦三角等离子体中正电子的加速

应用多光子非线性Compton散射模型和数值模拟方法,研究了正弦三角超强激光等离子的尾场对正电子加速,提出了将入射超强激光和非线性Compton散射光作为等离子体尾场对正电子加速的新机制,给出了正电子加速能量修正公式和数值模拟结果。结果表明:使用非对称正弦三角激光脉冲的等离子体尾场加速正电子优于对称正弦三角激光脉冲的尾场情况,散射使非对称正弦三角耦合激光脉冲宽度和上升长度与下降长度之比缩小,正电子获得的加速能量显著增大。这是因为正电子频率增大,横向速度各向异性分布增强,尾场限制了正电子横向加速能量,导致正电子在激光传输方向加速能量增大。     

激光等离子体中的自生磁场和质子加速

选用不同类型的等离子体薄靶,用二维particle-in-cell(PIC)粒子模拟方法系统研究了超强激光脉冲与等离子体薄靶相互作用中产生的自生磁场和质子加速行为,结果发现:当功率密度为1020W/cm2的超强激光与等离子体薄靶相互作用时,由于等离子靶面所产生的自生磁场作用使产生的质子分布呈现空间定向发射,发射的方向和高能质子能量与等离子体靶面密切相关,能量越高发散角越小,而质子加速越好。在圆形薄靶中质子最大能量达到41.1 Me V。研究结果对惯性纳米聚变快点火和肿瘤治疗等方面具有重要的应用价值。     

激光核聚变中自生磁场与热输运的粒子模拟

利用相对论电磁粒子模拟程序研究了超强激光与等离子体相互作用过程中产生的自生磁场和电子热输运特性。讨论了自生磁场产生机制和非线性饱和过程。给出了自生磁场的线性增长率和各向异性参数之间的函数关系,用Spitzer-Harm理论分析了电子热传导中能量的运输情况,观察到由激光的非等方加热引起的电子纵向加热现象。细致研究这些过程对更好的理解快点火物理中自生磁场的产生、超热电子热输运等过程有重要意义。     

超强激光与等离子体平面靶相互作用中的自生磁场

为了解释超强激光与等离子体相互作用时产生的自生磁场及其产生机制,从动力论出发,用理论分析和数值模拟法研究了强激光打平面薄靶时,由温度梯度和密度梯度的非共线性所决定的自生磁场,得到了自生磁场空间分布的时间演化关系。研究结果表明,当激光入射等离子体时,由于不平行的密度和温度梯度,在等离子体表面会出现自生磁场。这种磁场明显地影响激光吸收和各种输送过程。     

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.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

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.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.