有中心缺陷孔的矩形点阵PCF双折射特性研究

采用全矢量有限元法研究了具有中心椭圆缺陷孔的矩形点阵PCF(光子晶体光纤)的双折射特性。结果发现,该新型PCF的双折射特性对波长和光纤的结构参数具有较强的依赖关系,与无中心椭圆缺陷孔的矩形点阵PCF相比,在中心缺陷孔参数bc/Λ=0.075、中心空气孔椭圆率η=2.2、包层结构参数Λ=2.0μm和d/Λ=0.48时,该新型PCF具有更高的双折射。     

低有效模场面积的高双折射PCF的优化设计

设计了一种高双折射低有效模场面积的光子晶体光纤(PCF)。利用有限元法依次研究了三层椭圆孔光子晶体光纤在纤芯中引入矩形排列的四个小椭圆孔,及其基础上再引入一个中心椭圆缺陷孔的五个小椭圆孔情况下的双折射和有效模场面积。研究表明:纤芯区域矩形排列的小椭圆孔主导了光子晶体光纤的双折射,中心椭圆缺陷空气孔中填充高折射率的材料可以获得更高的双折射和更低的有效模场面积,且波长1.55μm处光纤双折射达到了5.49×10-2,x与y偏振有效模场面积分别低至3.05μm2、2.42μm2。     

双芯光子晶体光纤温度传感特性的研究

设计了一种双芯光子晶体光纤(PCF),并在其两个纤芯中填充混合热敏液体,采用全矢量有限元法和光纤模式耦合理论,研究了温度对填充后PCF的有效折射率、双折射、耦合长度以及限制损耗的影响。研究表明,参量对温度比较敏感,且PCF双折射达到10-3数量级。     

高非线性高双折射光子晶体光纤特性的理论研究

基于全矢量有限元法,设计了一种新型零色散波长为1550 nm的高非线性双折射光子晶体光纤(PCF),并分析了PCF的有效折射率、有效模面积、双折射、非线性系数以及色散特性。数值结果表明,当光纤包层孔间距Λ为1.6 μm,大空气孔直径d1为1.4 μm,小空气孔直径d2为0.74 μm和0.76 μm时,光纤的零色散波长都在1550 nm处,该PCF的双折射为4.049×10-3,非线性系数可达28.4 km-1·W-1。这种高非线性高双折射PCF,在1550 nm通信波段具有非常广泛的应用前景。     

光子晶体光纤损耗特性的数值研究北大核心

为了理论分析PCF(光子晶体光纤)的损耗特性,采用多极法研究了包层空气孔直径、孔间距和空气孔层数等参数对PCF 1.31和1.55μm波长处损耗特性的影响。结果表明,选择高空气填充率的结构和增加包层空气孔层数都可以降低PCF损耗;通过增大最外层空气孔直径可在保持色散特性不变的情况下显著降低PCF的损耗。该结论可以为设计低损耗特性的PCF提供理论依据。     

高双折射双芯光子晶体光纤特性

提出一种新型的高双折射双芯光子晶体光纤(PCF)模型,通过将最内层8个空气孔替换为4个椭圆空气孔来增大光纤的结构不对称性;通过改变两纤芯间的空气孔大小、椭圆空气孔的椭圆度以及孔间距来分析光子晶体光纤的双折射度、耦合长度以及色散特性。结果表明,双芯光子晶体光纤的模式双折射度达到10-2量级,耦合长度达0.1367 mm,在1.0~1.6 μm波长范围内具有超平坦色散特性。     

基于液体填充的光子晶体光纤温度传感特性分析

提出了一种基于在折射率引导型光子晶体光纤(PCF)中填充高折射率温度系数液体的新型折射率型光纤温度传感器.通过建立理论模型,设定入射波长和材料参数及完美匹配层边界条件,采用全矢量有限元法对六角形结构排列的折射率引导型光子晶体光纤的温度特性进行了分析.研究表明,在空气孔中填充液体乙醇,PCF模场分布随着温度变化明显,其有效折射率和限制损耗都随着温度升高而减小.相同的孔间距,占空比越大,输入波长越长,有效折射率和限制损耗受温度影响越大.当波长为1500 nm,占空比为0.7,温度从-20℃升至70℃时,限制损耗从3.5×102dB/m减小到22 dB/m.     

双矩形纤芯光子晶体光纤偏振分束器

基于双折射效应设计了一种新颖的纤芯为椭圆空气孔,包层为圆形空气孔的矩形双芯光子晶体光纤偏振分束器。用半矢量光束传播法(BPM)数值模拟了基模情形下该偏振分束器的性能,结果表明:在工作波长为1.55μm,光纤长度为1659μm时,两个纤芯在X、Y方向偏振光的隔离度分别达到了-41.3 dB和-39.1 dB,隔离度小于-10 dB的带宽超过了80 nm,达到了良好的偏振分束性能。同时,模拟了实际加工误差对所设计的偏振分束器的影响,得出在1.55μm的工作波长下,误差达到±7%时,隔离度仍能小于-10 dB,具有较高的实际应用价值。     

一种Sagnac干涉仪结构的光子晶体光纤温度传感器

采用Sagnac干涉仪结构,设计了一种高双折射光子晶体光纤环镜温度传感器。光子晶体光纤温度稳定性好,通过向高双折射光子晶体光纤空气孔填充热光系数高的液体材料乙醇,从而实现温度传感的目的。采用平面波展开法,分析了高双折射光子晶体光纤的双折射与传输波长和温度的关系。理论分析表明,填充乙醇后,高双折射光子晶体光纤的双折射随着传输波长和温度的增加而增加,且双折射与温度成线性关系。实验中将一段填充乙醇的高双折射光子晶体光纤与3 dB耦合器熔接制作成Sagnac干涉仪结构的光纤环镜,当温度从 45 ℃升至80 ℃时,光谱仪上观察到凹点λi向短波方向漂移了309.280 nm,温度灵敏度高达8.837 nm/℃。     

填充混合液体的光子晶体光纤温度传感研究

为获得高灵敏度光子晶体光纤温度传感,在实心光子晶体光纤（PCF）空气孔中填充氯仿和酒精等高折射率热敏液体的混合物。理论上采用有限元法分析了温度对光纤模场面积和限制损耗的影响。通过调节液体的混合比,使损耗对温度的灵敏度达到最大值,实现了高灵敏度PCF温度传感。实验表明,填充液体的长为4mm的PCF温度传感器,灵敏度经检测...     

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