二维光子晶体波导和微腔缺陷态研究

利用二维三角晶格及正方晶格介质柱光子晶体TE偏振的禁带与介质柱半径的变化关系,分析了二维光子晶体缺陷态的分布.根据光子晶体波导间的耦合作用,计算其耦合长度设计合理的定向耦合器.通过分析波导与微腔的耦合特性,选取不同的传输方向,可以设计多种基于光子晶体波导与微腔耦合的波分复用系统.     

基于锯齿口和多支路的二维光子晶体出射光集束

光子晶体波导具有传输速率大、损耗率低、稳定性好等特点,在光集成、光信息传输等领域具有十分广阔的应用前景.然而作为亚波长波导,由于存在衍射极限,光子晶体波导的出射光会发散到各个方向,影响出射光集束.为解决光子晶体波导出射端光场控制问题,提出了一种新型的二维正方晶格光子晶体出射光集束的结构.该结构通过在波导出射端表面引入锯齿口结构和多支路通道,大幅度提升了出射光的辐射距离.利用时域有限差分法分析结果表明,具有3个锯齿口和2条支路的正方晶格光子晶体能够实现最佳的出射光集束,辐射距离高达200 μm,该辐射距离约为单波导出射端结构的25倍,且该结构在200 μm处的辐射效率可达53％.     

基于多模干涉的二维三角晶格光子晶体分束器

光分束器光接入系统的核心器件,是光子多功能设 备和系统的关键构成模块,为满足急速增长的数据通信业务对光分束器的需求,本文在完整 三角晶格光子晶体中引入五条平行光子晶体波导组成多模干涉 系统,利用自成像效应的多模波导与微腔耦合,提出了一种新型二维三角晶格光子晶体四端 口分束器。利 用时域有限差分法进行仿真分析,结果表明:在一定范围内通过改变输出端四个耦合微腔内 的介质柱半径, 可以保证在分束器拥有较高的透射率的同时,且能实现输出能量的均分或在一定范围内的自 由分配。     

光子晶体波导定向耦合功分器的设计

将相互耦合的3平行光子晶体单模波导看成一个多模干涉系统,通过研究二维正方晶格光子晶体波导多模干涉的自映像效应,优化设计了一种新型1×2光子晶体波导定向耦合分束器,采用时域有限差分法对其传输特性进行模拟分析。设计过程中,根据多模干涉耦合区中周期出现的双重像的位置确定两个单模输出波导的位置,通过改变输出波导和耦合区连结的一个介质柱位置构成波导微腔结构,改变耦合区中的模场分布,实现模式匹配,从而明显减小分束器的反射损耗。计算结果表明,移动介质柱距离输出单模波导和多模波导连结处1.85a位置处时,对于波长为1.55μm的入射光,该分束器的透射率可高达99.04%。     

二维三角形光子晶体带隙与耦合特性研究

利用二维三角晶格介质柱光子晶体TE偏振的禁带与介质柱半径的变化关系,分析了二维光子晶体的带隙分布及斜边耦合特性.结果表明,光子禁带的大小受到构成光子晶体的介电材料的空间排列分布以及介质柱半径大小的影响;束缚在光子晶体中的光波可以在波导和谐振腔中进行传输,达到选择输出光波的目的.     

二维光子晶体波导的能带分析

设计了在25×13的二维圆柱正方晶格中心引入线缺陷构成的光子晶体波导,利用平面波展开法(PW E)方法计算并仿真了该波导的能带分布,分析出其带隙分布与介质柱折射率和占空比的关系,总结出了能带与两者之间的变化规律,得出了存在最大带隙结构的波导参数是介质柱的折射率为6.9,占空比2r/a=3.6,对于实际制作光子晶体波导提供了理论指导。     

空气孔型光子晶体带隙及波导耦合特性研究

为了研究2维三角晶格空气孔型光子晶体TE模和TM模偏振的禁带宽度与介质柱半径的变化关系,采用平面波展开法数值计算和分析了空气孔型光子晶体的带隙分布及波导耦合特性。结果表明,光子禁带的宽度会随着介质柱半径的大小而变化,束缚在光子晶体中的光波可以在波导和谐振腔中高效率地传输,达到选择输出光波的目的。这种特性在光学集成电路中具有重要而潜在的应用价值。     

折射率可调的二维光子晶体设计与特性

光子晶体在传感、滤波和光子晶体激光器等方面具有很重要的应用价值。设计了一种基于改变缺陷介质折射率的可调谐二维正方晶格和三角晶格光子晶体激光器微腔,在平面光子晶体薄板中引入点缺陷磷酸氧钛钾(KTP),在KTP两端施加交流电场控制KTP晶体折射率变化。实验中随着KTP晶体折射率逐渐增大,正方晶格光子晶体禁带数量减少,归一化频率减小,禁带宽度基本不变;而三角晶格光子晶体禁带逐渐变窄,且向低频方向移动。最后,用平面波展开法分析了晶体的能带结构,得到理论上的描述,验证了实验结果。     

二维光子晶体窄带滤波器研究

由于光子晶体存在带隙,只要在完整的二维光子晶体中引入线缺陷,那么原来处于禁带处特定波长的光也能沿着形成的波导传播,从而该光子晶体就具备了滤波的功能,再在线型波导的一侧设计个点缺陷,利用时域有限差分法分析发现,在缺陷处耦合出来的光不仅仅光强增大了,而且半高宽也变小了,这就与窄带滤波器的功能十分吻合。此外,只要根据光子晶体的晶格常数和椭圆介质柱的半径与窄带滤波器的中心波长关系,通过调整光子晶体的晶格常数和介质柱的半径,就可以改变窄带滤波器的中心波长。     

GeSbSe光子晶体波导结构设计及传输特性研究

利用平面波展开法计算Ge Sb Se基质光子晶体带隙,研究光子晶体波导中带隙与空气孔(或介质柱)半径的变化关系,并结合光子晶体波导的工作波长,设计出周期为500 nm,半径为150 nm的三角晶格空气孔型Ge Sb Se光子晶体波导。采用时域有限差分法模拟所设计的直线型光子晶体波导和60°弯曲光子晶体波导的传输特性,模拟结果显示在传统结构光子晶体波导中,直线型光子晶体波导具有很高的光学传输效率,但在60°弯曲型波导中的传输效率较低,分析原因为光子晶体波导直线区域与弯曲区域光的传播模式不同。因此对60°弯曲型Ge Sb Se光子晶体波导进行了结构优化,优化后的光子晶体波导可以在较宽的波长范围内具有很高的传输效率。     

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.     

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.     

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.     

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.     

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.     

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.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.