大传输窗口低限制损耗空芯反谐振光纤的数值研究

提出了一种大传输窗口低限制损耗单环嵌套结构 的空芯反谐振光纤。采用全矢量有限元法结合完 美匹配层边界条件数值模拟了光纤传输特性,并分析了空芯反谐振光纤的结构参数对光纤传 输特性的影 响。仿真结果表明,优化后的光纤具有大传输窗口低限制损耗的优势,且具有平坦色散特性 。当纤芯直 径为50 μm、反谐振管个数N为6、反谐振 管厚度t为0.30μm、外层反谐振管直径d为32. 50 μm、内层 反谐振管直径d₁为21.13 μm时,在1 260—1 675 nm波长范围内,限制 损耗均低于0.21 dB/km ,色散值为(1.1±0.3) ps/(nm·km),在波长为1 550 nm时,限制损耗为0.078 dB/km。     

环烯烃共聚物空芯微结构太赫兹光纤的设计与制造

以环烯烃共聚物（cyclic-olefin copolymer,COC）材料为基质,设计、制造了一种空芯多孔包层太赫兹（THz）纤维。利用comsol 软件模拟了芯径为6 mm 的光纤在0.2~1.5 THz 波段的损耗特性,结果表明:在0.85~1.5 THz 波段存在多个低损耗频带,而且在0.85~1.1 THz 波段有低于3 dB/m 的三个窗口;特别是在0.99 THz,损耗达到0.208 dB/m。芯径为3 mm、4.8 mm 和6 mm 的光纤在0.8~1.5 THz 波段的损耗特性对比分析表明:该COC 微结构多孔包层空芯纤维的损耗随着光纤外径的增加而减小。把设计的太赫兹纤维外径放大7 倍达到7 cm,据此设计制造了光纤预制棒成型专用模具。借助热挤出成型方法得到了结构完整、孔洞表面光滑,长度为22 cm 的空芯多孔包层预制棒。利用该实验室独有的微结构光纤拉丝塔,成功获得了微结构保持完好的光纤样品。损耗分析结果表明:6 mm 芯径的光纤样品在1.27 THz 的平均损耗为2.175 dB/m,与该频率的理论损耗（1.95 dB/m）接近。     

用于激光能量传输的大纤芯微结构光纤的设计及制备

设计和制备了一种传输高功率激光能量石英基质微结构光纤。光纤的外径为180μm,芯径为84μm,包层为双层空气孔。实验结果表明,对半导体激光的980nm和YAG激光的1 064nm波长的传输损耗分别为6dB/km和7dB/km,而最低损耗可达到1dB/km@935nm;在弯曲半径为0.25cm的条件下,弯曲的附加损耗为0.56dB/circle@980nm和0.416dB/circle@1 064nm;实验测得在980nm波长的实际模场面积为2 951.71μm2,与理论值2 951.4μm2相吻合。研制的光纤具有结构简单、柔软性好、易制备、低非线性、低损耗和高损坏阈值等特点,是高功率激光能量柔性传输系统的理想介质。     

低折射率实芯Bragg光纤传输特性研究

Bragg光纤是一种新型的光子晶体光纤,具有径向一维周期性结构。随着Bragg光纤研究的不断深入,国内外提出了具有各种不同结构的Bragg光纤,不再局限于空芯Bragg光纤。这就使Bragg光纤的研究内容更加丰富,也使更多新颖的传输特性成为可能。提出了一种低折射率实芯Bragg光纤,纤芯用SiO2作为材料,包层用折射率略高于SiO2的介质和SiO2交替产生周期性结构。使用渐进矩阵法对它的传输特性做了初步研究,发现在较宽的频带内有很好的单模传输特性,其泄漏损耗在10^-3dB／km量级。     

单模光纤接续应注意的技术问题

单模光纤是在给定的工作波长中只传输单一基模的光纤,它不存在模式色散,所以具有相当宽的传输频带,运用于长距离大容量的传输.单模光纤的纤芯直径只有8～10 μm,包层直径为125 μm,可以制作得很长,但是为了制造、运输与施工的方便,通常光缆的出厂长度为1～6 km.单模光纤的传输损耗现低达0.2 dB/km(1.55 μm),光缆接续长度不宜小于2 km.     

太赫兹光子晶体光纤与天线设计

以聚甲基丙烯酸甲酯(PMMA)材料为基质,设计了一种空芯多孔包层结构的太赫兹光纤,中心的大孔缺陷用于传输太赫兹波,周围四层小孔可以将太赫兹波的传播限制在缺陷内部。利用COMSOL软件对光纤的损耗特性进行仿真分析发现,光纤在0.6 THz的泄露损耗低于0.1 dB/m,具有良好的传输特性。和金属波导口可以当作天线辐射电磁波的原理相似,光纤的端面也可以作为天线将内部传输的太赫兹波向外辐射,通过仿真分析,天线在0.59~0.61 THz的回波损耗低于-25 dB,方向性系数大于20 dB,半功率波束宽度约为13。     

一种新型超低损耗大有效面光纤的技术研究

采用双包层的波导结构结合纯二氧化硅芯的技术方案,通过包层氟掺杂的设计与芯/包层之间粘度匹配的优化,实现了超低损耗大有效面积ULA-130型G.654.E光纤的制造,然后利用自行搭建的光纤非线性系数测量系统和自主设计的光纤宏弯损耗松绕设备,结合现有技术对ULA-130光纤的各项性能技术指标进行了研究。该光纤在1 550 nm波长的衰减系数为0.159 dB/km,有效面积为133 μm²,非线性系数为1.67×10^-10W^-1。理论计算与技术研究结果表明,该光纤具有优异的衰减系数和非线性性能,适用于大容量、高速率和长距离光通信骨干网传输系统,相对于常规的 G.652.D 光纤,可以显著改善系统的光信噪比,提升系统的传输性能。     

包层折射率凹陷分布的单模光纤的特性

业已研制出VAD凹陷包层的单模光纤。所制备的光纤在纤芯中掺锗,折射率差为△~ =0.2～0.3％;在包层中掺氟,负折射率差为△~-=0.1～0.4％。包层与芯径之比为5到9,1.3μm波长处传输损耗小于0.5 dB/km。已发现,凹陷包层光纤侧向压力引起的弯曲损耗增加值与匹配包层光纤弯曲损耗增加值相等,匹配包层光纤的折射率差等于凹陷包层光纤折射率差的总和(△=△~ △~-)。但是,凹陷包层光纤的色散与纤芯中具有同样含锗量的匹配包层光纤的色散极其相似,即具有相同的正折射率(△=△~ ),使得1.3μm波长处的色散比较低。此外本文还证实了,这种光纤的熔融接头损耗与匹配包层光纤的熔融接头损耗一样小,在整个成缆过程中传输损耗始终很低。     

10.6μm空芯传能光纤的研制

为研制10.6μm空芯传能光纤,讨论了银层质量、碘化银层质量对空芯波导传输损耗的影响.介绍了研制波长为10.6 μm的空芯传能光纤的工艺方案及其典型参数.通过液相化学沉积法,在石英基底管内壁成功地生成了优质金属银层和碘化银电介质包层.制作了出具有高透过率的空芯红外波导.     

光纤衰减损耗综述

众所周知,在光纤线路中,最有影响的指标一是色散,二是衰减损耗。衰减是指光信号在光纤内的传输过程中产生的光功率损耗。衰减量是将每1km产生的损耗,用dB表示其值,例如单模光纤约为0.2dB/km,大约传输15km时损耗达3dB。     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks