一种宽角度极化不敏感的高可调谐红外超材料完美吸波体（英文）

提出了一种高度可调、宽角度且具有完美吸收和极化不敏感的超材料吸波体.模拟的结果显示,在5.8μm处可达到最高吸收率99.9%;通过改变其几何参数,吸波体的谐振波长在3.4μm到8.6μm的范围内可任意地调节,且都具有不低于95%的峰值吸收率.在横磁波下,当入射角度小于80°时,吸波体的吸收率保持在95%以上;在横电波下,当入射角小于60°时,吸收率保持在92%以上.此外,极化角度在0到90°变化时,吸波体具有极化不敏感性.     

双频段太赫兹超材料吸波体的设计及传感特性研究

提出了一种基于不同半径金属圆环加载于介质层的新型太赫兹超材料吸波体,实现了双频段的完美吸收和偏振不敏感性,且具备宽角度入射时可达到良好吸收的性能。仿真结果表明,该吸波体在f1 = 2.335 THz 和f2 = 4.215 THz 均可实现完美吸收,吸收率高达99. 99%;当入射角度达到70°时吸收率仍能保持80%以上。进一步分析可知,两个吸收峰分别由半径不同的金属圆环谐振产生,故而吸收峰的谐振频率可以通过调节圆环的半径进行单独调制。此外,还研究了该吸波体在介电传感和厚度传感两方面的应用。结果表明该吸波体对介电常数小于10的物质具有较好的传感性能,且吸收峰f2 的灵敏度较高;而应用于厚度传感时,吸收峰f1 的稳定性更适宜。研究结论对于设计新型超材料吸波体及其在传感中的应用具有重要意义。     

基于钒的表面等离子体宽带广角红外光吸收器

探讨了基于金属钒亚微米结构的表面等离子体宽带广角红外光吸收器,它由置于表面涂覆介质层的金属钒衬底上方周期性排列的无限长钒条构成。使用有限元方法计算了其吸收谱,当P极化平面电磁波以小角度(小于20°)入射时,吸收率达到98%以上,波长为1.08～1.60μm;当P极化平面波以大角度(小于50°)入射时,吸收率达到98%以上,波长为1.08～1.44μm;当P极化平面波以10°入射时,谐振峰(λ=1.54μm)的吸收率达到99.9%。此外,由于金属钒的熔点很高,基于金属钒的吸收器可用于强光高功率的场合。     

基于宽带吸波体的低雷达散射截面平面印刷磁电偶极子天线设计

该文设计了一种工作于X波段的平面印刷磁电偶极子天线,并设计了一种加载集总电阻的宽入射角、极化不敏感、宽频带吸波体(WBMA)。当平面波垂直入射时,吸波体在7.2~12.6 GHz范围内的吸波率大于90%,入射角增加至45时仍能在X波段保持90％以上的吸波率。通过将WBMA加载在天线四周,实现了天线雷达散射截面(RCS)的大幅缩减。实测和仿真结果表明:不同极化波垂直入射时,天线单站RCS减缩3 dB带宽为6.6~14.4 GHz,最大减缩量达23.8 dB。中心频点10 GHz处,TE极化波照射时,双站RCS能实现90角域内的减缩,TM极化波照射时,在35角域内实现了减缩,同时天线辐射性能几乎保持不变。     

基于等效传输线理论的高效超宽带吸波体

设计了一种基于氧化铟锡(ITO)薄膜的宽带吸波体,该吸波体在1.92~13. 15 GHz 之间实现90%以上吸波,绝对带宽达到11.12 GHz,相对带宽达到149.04%,完全覆盖了S、C、X 波段,部分覆盖了L波段和Ku波段,峰值吸收率达到了99%以上。文中采用BP神经网络快速精确计算出方环与方贴片所构成的表面结构的等效阻抗;仿真对比了不同层数的影响并通过遗传算法对单元结构参数进行优化;基于等效传输线理论,解析表达优化后单元的反射率并与实际仿真结果进行了对比。仿真与测试结果显示不同极化和不同斜入射角情况下,单元的吸收率曲线变化较小,说明该结构具有极化不敏感和大入射角特性。提出的方法解决了传统经验公式对结构参数普适性不足的问题,由于使用ITO作为表面结构,其阻抗实部可调范围广,在理论上无需扫参,可以快速精确地设计任意波段吸波的吸波体。     

一种新型可调谐宽带吸波器的设计

设计了一种新型可调谐且极化不敏感的宽带吸波器。采用了全波仿真方法对该吸波器的吸收率、电场图和表面电流图进行了计算, 并探讨了结构参数z、y 和入射角度啄对吸波器电磁波吸收特性的影响。研究结果表明, 该吸波器在12.17 ~14.19 GHz 频域的吸收率达到90% 以上, 通过激励不同的等离子体谐振区域不但可以改善其吸收特性, 实现吸波器的宽带吸收, 而且还能获得可调谐的吸收频谱。改变结构参数z 和y 可以在拓展吸收带宽的同时使吸收频域发生移动; 且该吸波器具有较好的角度稳定性。     

一种基于多层电阻膜的超宽带超材料吸波体

本文提出了一种基于多层电阻膜的超带宽超材料吸波体的设计模型.该吸波体的结构单元由一种环形电阻膜片在含导体底面的平面分层介质基板上多层叠加而成,各层电阻膜片的外形相同,但表面阻值不同.一件四层吸波体的仿真分析结果表明:该吸波体对6.8GHz~59.6GHz频段之间的垂直入射波吸波率均大于90%;同时对入射角为45度的TE和TM斜入射波仍能保持超宽带吸波,具有极化不敏感和宽入射角特性.另外,对不同层次吸波体的分析表明:随着电阻膜片层次的增加,其吸波效果更好,吸波频带变宽,带内吸波效果更稳定.     

基于石墨烯超材料的宽频带可调太赫兹吸波体

基于二维材料石墨烯,设计了一款宽频带可调谐超材料太赫兹吸波体。该吸波体由三层结构组成,顶层为石墨烯超材料,中间层为二氧化硅,底层为金属薄膜。仿真结果表明,当石墨烯的费米能级为0.7 eV时,该吸波体在1.11~2.61 THz频率范围内吸收率超过90%,相对吸收带宽为80.6%。当石墨烯的费米能级从0 eV增大到0.7 eV时,该吸波体器件的峰值吸收率可以从20.32%增大到98.56%。此外,该吸波体器件还具有极化不敏感和广角吸收的特性。因此,它在太赫兹波段的热成像、热探测、隐身技术等领域具有潜在的应用价值。     

太赫兹宽频带准全向平板超材料吸波体的设计

在太赫兹波段设计了一种宽频带准全向的平板超材料吸波体.仿真结果表明,该吸波体在4.36～4.91THz之间具有极化不敏感和宽入射角的强吸收.提取的等效阻抗实部表明,可以通过调节超材料的电磁响应造成吸波体一侧与自由空间近似阻抗匹配、另一侧与自由空间阻抗不匹配,从而在吸收频带内同时实现反射率和传输率最小、吸收率最大.仿真的...     

基于二氧化钒的动态可调谐的红外线超宽带吸收器

设计了一种基于二氧化钒的动态可调谐的红外线超宽带吸收器。数值模拟表明：对于横磁(TM)波,当入射角由0°增加到60°时,在17～55μm波长范围内,吸收器的吸收率可以保持在90%左右;对于横电(TE)波,当入射角由0°增加到55°时,在10～55μm波长范围内,依然可以实现90%左右的高效吸收;当TM波或TE波垂直入射时,在16～60μm波段,吸收率大于90%,吸收带宽可以达到54μm。当二氧化钒的电导率从20 S/m逐渐变化到2×10⁵ S/m时,超宽带吸收器可转换为多峰吸收器。与之前报道过的基于二氧化钒的吸收器相比,所设计的吸收器的带宽和可调性得到了显著改善。该吸收器有望在偏振探测器、热辐射器、红外传感器等领域中得到应用。     

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.     

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.     

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.