小振幅近似与形变超晶格系统的动力学稳定性

假设超晶格的"锯齿形"沟道对粒子的作用可等效为形状相似的周期调制,引入正弦平方势,并在小振幅近似下,把粒子运动方程化为具有硬弹簧特性的Duffing方程.利用多尺度方法分析了共振线附近的粒子运动行为,讨论了系统的主共振、子共振和超共振.计算了超晶格"锯齿形"沟道的临界斜率与系统参数之间的关系,为能带工程或超晶格光磁电效应的进一步研究提供了理论分析.     

小振幅近似与形变超晶格系统的动力学稳定性

假设超晶格的"锯齿形"沟道对粒子的作用可等效为形状相似的周期调制,引入正弦平方势,并在小振幅近似下,把粒子运动方程化为具有硬弹簧特性的Duffing方程.利用多尺度方法分析了共振线附近的粒子运动行为,讨论了系统的主共振、子共振和超共振.计算了超晶格"锯齿形"沟道的临界斜率与系统参数之间的关系,为能带工程或超晶格光磁电效应的进一步研究提供了理论分析.     

基于级联随机共振与APSO算法相结合的信号检测方法

针对随机共振方法以系统的参数和噪声强度的匹配为研究背景的局限性,为解决级联双稳系统参数的合理选取的问题及克服自适应随机共振单参数优化的不足之处,提出了一种基于级联随机共振与自适应粒子群(APSO)算法相结合的方法。该方法以系统的输出信噪比为优化目标函数,采用自适应粒子群算法较强的全局搜索能力和粒子(待优化参数)的多样性,对级联双稳态随机共振的级联系统参数进行同步优化,使系统处于最佳随机共振工作状态。仿真结果表明,该方法可以提高输出信噪比及算法的收敛速度,实现良好的检测效果。     

高频调制与储存环中粒子纵向运动的稳定性

考虑到运动阻尼、高频噪声和系统非线性等因素的影响,把储存环的同步运动方程化为含有阻尼项、受迫项和高阶相移因子的非线性微分方程。用摄动法导出了系统的近似解,并分析了系统在共振线附近的运动行为。揭示了系统跳跃现象和临界特征,分析了系统的数学稳定性和物理稳定性。结果表明,当三阶非线性相移因子小于零时,系统可以实现三束储存。     

超晶格量子阱的沟道效应与光学双稳态效应

构造了一种高阶非线性"抛物线"量子阱,并提出了一种获得光学双稳态的新概念.指出了只需在超晶格量子阱的两端加上一个直流电场和交变电场,便可用它作为光学双稳态器件.引入高阶非线性"抛物线"势,并考虑到粒子运动阻尼和外场作用,在经典力学框架内和弱偏置下,粒子运动方程化为了具有硬弹簧特性的Duffing方程.用摄动法找到了系统的近似解,并分析了共振线附近粒子的运动行为与系统的稳定性.结果表明,粒子的振幅平方与外场振幅平方的关系曲线出现了后弯现象,正是这个后弯现象决定了系统存在双稳态,也正是这个双稳态决定了具有四阶非线性抛物线势阱的超晶格量子阱可望作为光子或光电子技术中新的记忆元件或存储元件.     

开放的四能级双驱动场无反转激光系统研究

提出了开放的四能级双驱动场无反转激光系统的理论模型,由电偶极和旋转波近似得到其密度矩阵方程,在共振条件下,讨论无反转激光产生的物理机制,求得定态共振线性解析解,利用数值计算结果分析了能级间的自发衰减速率、非相干泵浦速率、粒子注入速率和粒子退出速率对系统无反转激光增益和粒子数差的影响,讨论了线性和非线性增益和粒子数差的差别.结果表明:适当的自发衰减速率、调节非相干泵浦速率、粒子注入速率和粒子退出速率可获得无粒子数反转激光;线性和非线性的增益和粒子数差随驱动场Rabi频率的变化趋势一样,增益的线性稳定值大于非线性稳定值.     

含类Kerr介质的双光子Jaynes-Cummings模型中光子的反聚束效应

本文研究了一个初始处于基态或激发态的二能级原子被嵌制在充满了类Kerr介质的高Q腔里，与单模辐射场双光子相互作用的系统中光子的反聚束效应．着重讨论了类Kerr介质与单模辐射场非线性作用强度x在共振和非共振条件下对光场非经典特性的影响．     

Moriere势与晶体摆动场辐射的弛豫行为

在经典力学框架内和偶极近似下,利用Moriere势把粒子运动方程化为了具有软硬弹簧特性的广义Duffing方程,利用平均法分析了系统在主共振线附近的运动行为;对系统的稳定性和弛豫行为进行了讨论,并导出了系统的临界参数.结果表明,系统的稳定性与参数有关,适当调节这些参数,系统的稳定性就可以得到保证.     

基于随机共振的微弱信号检测

介绍随机共振(SR)方法的基本思想,并建立数学模型。随机共振系统是非线性双稳态系统,存在某一最佳输入噪声强度,使系统产生最高信噪比输出,达到抑制噪声,放大微弱信号的目的。针对传统系统随机共振只适用于极低频信号的局限,本文引入尺度变换,消除了对待检信号频率的限制,通过Matlab仿真,验证了其对微弱信号检测的有效性。     

Ni(mpo)2的近双光子共振光学非线性特性的研究

采用脉冲宽度为7ns、波长为532nm的激光束，首次利用Z-扫描技术测量了新型功能配合物材料Ni（mpo）2[分子式C10H8N2NiO2S2]的非线性吸收系数和非线性折射系数。用粒子数重新布居模型，合理地解释了非线性吸收和非线性折射的产生机理：非线性吸收来自于近共振双光子吸收，而非线性折射是由于近共振双光子吸收造成的折射加强。非线性吸收系数和非线性折射系数随光强的增大而线性减少是近共振双光子吸收引起粒子斯雷斯布屠的结果。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.