FTTH用超低弯曲损耗单模光纤

美国康宁公司的科研人员设计并制造出一种带有纳米级特色环的新型超低弯曲损耗单模光纤。已经证明,该光纤在1550nm波长下和5mm弯曲半径时的弯曲损耗小于0．1dB／圈,其它光学性能参数与标准通信级单模光纤完全一致。     

新型低弯曲损耗光子晶体光纤的研究

提出了一种新型掺锗芯低弯曲损耗光子晶体光纤。通过调整结构参数,实现了单模低弯曲损耗传输,与标准单模光纤有较好的适配性。仿真结果表明,波长1550nm处,弯曲半径为5mm时,基模损耗为0.014dB/km;弯曲半径为4mm时,基模损耗为0.42dB/km,能承受的弯曲半径小。显示了光子晶体光纤具有成为光纤到户"最后一公里"主要通信介质的性能优势。     

FTTH用新型微结构光纤的设计与开发北大核心

为了开发适合FTTH(光纤到户)应用的抗弯曲光纤,设计并制备了一种12孔的空气石英复合微结构光纤。该光纤具备良好的抗弯曲特性,并与G.652D光纤具有良好的兼容性,在弯曲半径为2.5 mm的情况下,1 550nm弯曲附加损耗<0.10dB,与G.652D单模光纤的熔接损耗<0.15dB。     

高兼容性超低弯曲损耗单模光纤的制备与表征

介绍了一种新型非光子晶体结构弯曲不敏感单模光纤的设计与制备。采用数值计算方法分析了光纤的下陷型波导结构,通过PCVD(等离子体化学气相沉积法)工艺获得了1 310nm波长的模场直径为4.3μm、1 550nm波长的模场直径为5.4μm的光纤样品,与G.652D光纤的双点接续损耗低至0.15dB,满足普通跳线的接续要求。该样品在2.5mm弯曲半径条件下弯曲10圈,其1 550nm波长的弯曲损耗优化至0.01dB,可适用于任何苛刻的FTTx应用环境,并有替代铜缆成为消费电子中理想传输介质的潜力,同时还可用于各种光电器件中。     

单模光纤弯曲损耗的测量与分析

提供了弯曲半径从1．7mm到5．8mm，波长从1520nm到1565nm范围内单模光纤弯曲损耗的测试结果。观察到了弯曲损耗呈震荡变化、随着弯曲半径的增加损耗减小，振幅减小，随着波长的增加损耗增加、振幅增大的现象。并利用光纤的耦合模理论对单模光纤弯曲损耗震荡进行了解释。     

面向通感一体系统的耐弯三芯光纤

为了同时兼顾狭小空间下的光纤数据通信与环境感知,设计并制备了一种面向通感一体系统的耐弯三芯光纤。该光纤采用三角形纤芯排布和深掺氟折射率沟道结构,标准外径为125μm,优化了O波段(1 260～1 360 nm)的传输特性,具有与G. 657. A1光纤相似的布里渊增益谱(BGS)分布。测试结果表明：在1 310 nm波长处,芯层的平均损耗为0.58 dB/km,平均芯间串扰低于-50 dB/km;当最小弯曲半径R=10 mm且缠绕50圈时,光纤的弯曲损耗低于0.1 dB。     

400Gbit/s高速大容量光通信系统单模光纤设计与制备

介绍了一种大有效面积单模光纤的数值设计分析与PCVD(等离子体化学气相沉积)制备工艺,该光纤的有效面积达到133μm2,同时在1 550nm处衰减系数优化到0.183dB/km,弯曲损耗优化至0.45dB/圈(弯曲半径7.5 mm)。在双偏振DFT-S CO-OFDM 4QAM/16QAM(4进制/16进制正交振幅调制的离散傅里叶变换扩展相干光正交频分复用)调制信号下,对该光纤在100Gbit/s和400Gbit/s系统的误码率和Q值等传输性能进行了验证。结果表明,该光纤能有效改善最佳入纤功率和非线性效应,可使传输距离提升30%,能有效优化400Gbit/s传输系统,并且在FTTx领域有着广泛的应用前景。     

超低损耗孔助光纤弯曲性能优化设计

建立了弯曲光纤的二维轴对称有限元分析模型,对初始光纤弯曲性能进行了有限元分析,分别计算其弯曲损耗,有效模场面积和连接损耗;选取芯层到下陷层距离b,下陷层宽度c,下陷层深度t,空气孔孔径r为设计变量,以弯曲损耗和连接损耗最小为目标,利用正交试验和灰度关联分析相结合的方法对光纤弯曲性能进行了多因素多目标优化设计。研究结果表明:优化后光纤弯曲损耗从0.127 8 dB/m减小到1.749 810-4 dB/m;有效模场面积从94.741 m2减小到82.37 m2;连接损耗由0.174 3 dB减小到5.80510-4 dB。与标准单模光纤对比发现,新型光纤在弯曲半径为3 mm的情况下,有效模场面积从209.21 m2减小到82.3 m2,连接损耗从7.535 8 dB减小到5.80510-4 dB,大大地降低了光纤的连接损耗。新型光纤在小半径弯曲情况下,也能保证系统的传输质量。     

新型大模场光子晶体光纤传输系统及其传输特性分析

通过在多模光子晶体光纤的两端分别连接一根单模光子晶体光纤,对其选择合适的参数,形成一种可以实现低弯曲损耗、大模场单模传输的光纤传输系统。运用数值仿真,分析了该传输系统在模场面积、弯曲损耗、连接损耗等方面的特性。研究结果表明,多模光子晶体光纤与单模光子晶体光纤所组成的系统可实现有效的单模传输;工作波长为1064nm时,多模光子晶体光纤在直波导状态时的基模模场面积可达1593μm2;在弯曲半径低至10cm时,多模光子晶体光纤仍然可以保持低损耗传输。经过对多模光子晶体光纤结构参数的优化,其与单模光子晶体光纤的连接损耗降低至0.085dB。     

400Gbit/s光通信用超低损耗超大有效面积光纤的研究

从电磁场基 本理论出发,采用标量波动方程进行分析与计算,设计出一种超低损耗超大有效面积单模光 纤(SMF)的折 射率剖面结构,纤芯折射率为1.461,纤芯直 径为13.99μm,内包层引入低折射率下凹 环,其折射率为1.455,宽为 6.95μm;采用连续化学气相 沉积(CCVD)工艺,制造出包层直径为125μm的SMF。测试表明,研 发的光纤具备超低损耗 与超大有效面积特性,其在1550nm波长的衰减 为 0.165dB/km,在1625nm波长的衰减为0.179dB/km;在 1550nm波长的模场直径为13.96μm,有效面 积为153μm²;光纤具备优良的抗弯曲性能,在弯曲半径为30mm 的芯轴上弯曲100圈的条件下, 其在1550nm的弯曲附加损耗为0.032dB,在1625nm波长的弯曲附加损耗为0.093dB。实验结果表明, 本文研发的SMF能够满 足400Gbit/s高速光通信的应用需求,可为下一代高速光纤通信提供 关键基础材料支撑。     

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