巷道中电磁波传输特性研究

随着通信技术的发展,地面移动通信技术在不断提高,但是煤矿井下移动通信技术进展缓慢,主要是由于矿井下恶劣的通信环境以及对通信的特殊要求。为了使复杂的问题简单化,文章将矿井巷道理想化,根据理想波导理论,研究了直巷道内电磁波的传输特性和损耗特性,并且估算了TE10波在一定的巷道壁电导率情况下的损耗和传输距离,本文对巷道内无线电通信的发展有着重要的理论指导意义。     

电容加载共面波导移相器的损耗特性

借助仿真软件Sonnet研究了金属导电层厚度、电导率和铁电薄膜介质损耗对移相器传输损耗和反射损耗的影响。结果显示:导电层的厚度超过2.0μm后,移相器的传输损耗不再随导电层厚度的增加而改变;随着导电层电导率的增加,移相器的传输损耗在高频段迅速减小;随着铁电薄膜介质损耗的减小,移相器的传输损耗在高频段下降很快;当介质损耗小于0.001时,移相器的传输损耗几乎不再减小。前述三种因素对反射损耗基本无影响。     

光纤弯曲损耗的影响因素及其对策

传统的光信号传导模式是直线传输,与光纤传输相比它的投入成本较大,光纤传输在通讯领域的运用很大程度的节约了光纤投入成本,但受到弯曲部分的影响,每经过一个弯曲处光信号就会损耗一部分,因而信号传输距离决定了光信号的接受灵敏度。在光纤弯曲中弯曲半径与损耗成正比,弯曲半径越大损耗就越小,波长不同受到的损耗也不相同,探究影响光纤弯曲损耗的因素也就具备了现实意义。本文针对光纤弯曲损耗问题进行探究,具体分析了影响光纤弯曲损耗的因素,简单叙述了相应的光纤弯曲损耗测试和对策,以延长光纤的使用寿命。     

光纤应用损耗的研究及其对策

光纤的传输损耗特性是决定光网络传输距离、传输稳定性和可靠性的最重要因素之一。光纤传输损耗的产生原因是多方面的．在光纤通信网络的建设和维护中，最值得关注的是光纤使用中引起传输损耗的原因以及如何减少这些损耗。光纤使用中引起的传输损耗主要有接续损耗(光纤的固有损耗、熔接损耗和活动接头损耗）和非接续损耗（弯曲损耗和其它施工因素和应用环境所造成的损耗)两类。     

以微波方式进行电视信号传输时的系统指标分析.

系统阐述了影响微波传输的各种外界因素及微波传输特性,并且根据这些外界因素和传输特性对微波传输性能,传输余隙,噪声,损耗及电平裕量等进行了系统分析。     

基于433频段无线传输的试验研究

针对实际生产环境中对无线传输质量产生影响的因素,结合固态酿醋控制系统对433 MHz的无线传输模块进行试验研究。针对机械设备中存在的电磁波干扰、不同材质障碍物对无线信号的衰减损耗、不同房间不同楼层间传输的特性及特定环境下不同传输距离的误码率进行试验,重点衡量误码率、传输损耗、信号强度、传输距离等指标,试验结果可以为无线传输系统的设计提供参考。     

OTDR宏弯曲损耗测试的分析与应用

宏弯曲损耗已经成为影响FTTx线路传输质量的重要因素.通过分析宏弯曲损耗形成的机理,针对实际工程中弯曲损耗测量存在特点和问题,探讨了利用OTDR准确测试单模光纤中宏弯曲损耗的相关技术,为工程中正确应用OTDR检测光纤的宏弯曲损耗提供了参考.     

介质损耗对频率选择表面传输特性的影响

应用模匹配技术,研究了Y形缝隙平面周期阵列夹嵌于均匀有耗介质层中心的夹心频率选择表面(FSS)结构对平面波的传输特性。讨论了介质层对结构中心谐振频率、传输带宽、以及传输损耗的影响规律。相同介电常数的介质材料在有耗和无耗情况下的模拟分析结果清楚表明介质本身的损耗是影响FSS结构损耗特性的主要因素。     

电视信号微波传输时的系统指标分析

本文阐述了影响微波传输的外界因素有微波传输特性，并对微波传输性能、传输余隙、噪声、损耗、电平裕量及中断概率进行了系统分析。     

降低光纤熔接损耗方法浅谈

光纤通信凭借其传输容量大,保密性能好,通信距离远等特点,已成为当今最主要的有线通信方式之一。受光纤制作工艺、施工人员素质等影响,熔接损耗已成为制约光纤通信系统传输距离的重要因素。本文对光纤熔接损耗产生的原因进行分析概括,提出有效降低损耗的方法以供参考。     

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.