非傍轴截断双曲余弦高斯光束的M2因子

基于功率密度的二阶矩方法,对非傍轴截断双曲余弦高斯(ChG)光束的束宽、远场发散角和M2因子进行了研究.数值计算结果表明,非傍轴截断ChG光束的M2因子不仅与截断参数δ、偏心参数α有关,而且与初始束腰宽度和波长之比w0/λ有关.在δ足够小时,M2因子可小于1.当δ→ 0时,远场发散角趋于渐近值63.435°.对于α=0(Ω0=0)和δ→∞的特例,我们的结果分别退化为非傍轴截断高斯光束和非傍轴无截断ChG光束的M2因子.     

非傍轴余弦-高斯光束的传输

从功率密度的二阶矩方法出发,对非傍轴余弦一高斯(CoG)光束的传输特性进行了系统的研究.结果表明,基于二阶矩定义的束宽在传输过程中满足简单的双曲线变化规律.非傍轴CoG光束的M2因子不仅与偏心参数α有关,而且还与f参数有关.在1/f足够小时,M2因子可小于1.当1/f→0时,远场发散角趋于渐近值63.435°.对于α=0(Ω0=0)的特例,非傍轴CoG光束的M2因子退化为非傍轴高斯光束的M2因子.     

非傍轴旋转对称拉盖尔-高斯光束的远场发散角

基于功率密度的二阶矩方法,推导出了非傍轴旋转对称拉盖尔-高斯(LG)光束远场发散角的解析公式,并表示为伽玛函数的幂级数求和形式。计算结果表明,当初始束腰宽度和波长之比w0/λ趋于0时,对任意非傍轴旋转对称LG光束,远场发散角趋于渐近值63.435°,与阶数无关。对于p=0的特例,则退化为非傍轴高斯光束的结果。     

非傍轴厄米-正弦-高斯光束的特性

为了研究厄米-正弦-高斯(HSiG)光束在非傍轴情形下受参量影响的特性,基于光强二阶矩理论,经过一系列复杂的数学计算,得出了非傍轴厄米-正弦-高斯光束的远场发散角、束腰宽度以及光束传输因子的解析式,并通过数值模拟,得到了它们与离心参量的关系。结果表明,在束腰宽度与波长比取值逐渐减小时,随着离心参量趋于0,当阶数为奇数和偶数时.发散角分别趋于63.435°和73.898°。束腰宽度和光束传输因子随参量的增加呈现较大的起伏,非傍轴情形下的光束传输因子取值与傍轴情况有很大的不同,其受参量影响不仅可以小于1,甚至趋于0。     

非傍轴双曲余弦高斯光束质量因子的研究

运用非傍轴标量光束的光强二阶矩理论,计算了非傍轴双曲余弦高斯光束的束腰半径、远场发散角、质量因子,并与傍轴双曲余弦高斯光束的质量因子进行了比较研究。数值计算表明:当双曲余弦高斯光束束腰半径较大时,傍轴与非傍轴理论计算的光束质量因子变化规律完全相同;束腰半径较小时,傍轴理论的计算结果有较大误差。     

非傍轴截断余弦-高斯光束的轴上光强

基于瑞利衍射积分公式,以非傍轴截断余弦-高斯(CoG)光束为例,对非傍轴截断光束的两种光强表示式,即传统的光强定义和光强的精确表述进行了比较研究.数值计算结果表明,两种定义之间的差异与截断参数,偏心参数,wo/λ和z/λ有关,其中w0,λ和z分别别为束腰宽度,波长和传输距离.     

像散透镜对双曲余弦-高斯光束参量的影响

为了进一步研究双曲余弦-高斯光束的特性,从广义惠更斯-菲涅耳衍射积分公式出发,对双曲余弦-高斯光束通过像散透镜后的光束参量,例如束宽和远场发散角的相对误差作了研究.结果表明,束宽和远场发散角的相对误差与像散因子C2,偏心参量α,瑞利长度z0以及透镜焦距f等有关.几何焦面上x和y方向束宽的相对误差与像散系数C2和偏心参量α变化相同,而在像方束腰处两方向相对误差变化迥异.此外,束宽的相对误差还与传输距离z有关.因像散影响,在x和y方向远场发散角一般不相等,并且还与偏心参量α有关.     

湍流大气中部分相干双曲余弦高斯光束的M~2因子

基于广义惠更斯菲涅耳原理和维格纳分布函数的二阶矩方法,推导出部分相干双曲余弦高斯(ChG)光束在湍流大气中的束宽、远场发散角和M2因子的解析表达式。研究结果表明,部分相干ChG光束在湍流大气中传输时,均方根角宽度、M2因子和相对M2因子随着传输距离的增大而增大,且与束腰宽度、波长、离心参数、相干参数及湍流强度等有关;均方根角宽度随着光束离心参数的增大存在极小值。当传输距离较远时,随着离心参数的增大,M2因子存在极小值;离心参数较大的光束受湍流的影响较小。     

双曲余弦高斯光束在梯度折射率介质中的束腰宽度及其位置

为了研究梯度折射率介质中双曲余弦高斯光束的束腰及其位置,推导出了双曲余弦高斯光束在梯度折射率介质中的传输场,并运用空间二阶矩的定义解出了光斑尺寸、束腰宽度及位置的表达式,讨论了梯度折射率介质对双曲余弦高斯光束的光斑尺寸、束腰宽度及位置的影响。研究结果表明:梯度折射率介质中光斑尺寸随传输距离的增加出现了周期性变化,周期由折射率系数决定;随偏心参数的增大,束腰宽度先逐渐减小再逐渐增大后趋于稳定;并且发现偏心参数决定光斑尺寸振荡幅度。     

对激光光束质量一些问题的认识

从对激光光束质量研究进展开始,讨论了在傍轴和非傍轴范畴内激光光束质量的一些问题,主要是非傍轴光束的光束质量评价。光束传输的非傍轴矢量二阶矩理论可用于计算多种非傍轴光束的M2因子,但对M2因子的物理解释却有困难。例如,在非傍轴范畴,M2因子依赖于束腰宽度与波长之比,并可小于1。但远场发散角之值可趋于90°,这将导致很大的M2因子值。另一方面,若将公式中的光强用时间平均坡印廷矢量z分量代替,桶中功率(PIB),或等价地,?茁 参数可推广用于评价非傍轴光束的远场光束质量。PIB表征了光束功率的可聚焦能力,是一种简明、直观评价不同激光光束的方法。然而,在?茁参数的公式中的束宽是按功率含量百分比定义的,因此双曲线传输规律不再严格成立。     

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.