弯曲的多模掺Yb3 + 双包层光纤激光器基模输出研究

将一段纤芯直径为28．6μm，数值孔径为0．10的掺Yb^3＋双包层光纤弯曲后可以得到基模激光输出，其输出最大功率为0．35W，中心波长为1073nm。实验结果和理论分析结果基本一致。     

弯曲的多模掺Yb3 + 双包层光纤激光器基模输出研究

将一段纤芯直径为28. 6μm,数值孔径为0. 10的掺Yb3 +双包层光纤弯曲后可以得到基模激光输出,其输出最大功率为0. 35W,中心波长为1073nm。实验结果和理论分析结果基本一致。     

大模面积双包层掺Yb3 光子晶体光纤激光器

报道了一种新型的、具有大模面积(LMA)的掺Yb^3 双包层光子晶体光纤(PCF)激光器。光纤的长度约为5m，光纤纤芯的直径为23μm，内包层的直径为420μm，数值孔径(对950nm)为0．55。输出激光的中心波长为1068．7nm，激光最大输出功率为4．26w。相对于入射的泵浦光，输出激光的转换效率为44．1％。实验结果表明，高功率激光输出存在着自脉动行为。     

国产25/400 μm掺镱光纤实现3.2 kW激光输出

利用改进的化学气相沉积工艺结合溶液掺杂技术制备了高光束质量的25/400 m双包层掺镱光纤。石英纤芯的掺杂组分为Yb2O3、Al2O3、P2O5,Al2O3有助于降低Yb3+团簇,增加Yb3+掺杂浓度,P2O5起到降低光子暗化效应的作用。纤芯-包层折射率差为0.001 2,纤芯的数值孔径为0.06。976 nm波长处的包层吸收系数为2.1 dB/m。构建双向抽运方式的主控振荡器功率放大器结构对增益光纤性能进行测试。实验中,1 080 nm种子光功率为235 W,在抽运光总功率为3 706 W时,实现了最大功率3 243 W激光输出,斜效率为81.1%,光束质量因子为1.7,未发生受激拉曼散射现象。光纤激光器连续工作1 h,输出功率未见明显变化。采用相同测试方法及平台对25/400 m型号的进口光纤进行测试,对比实验结果表明:实验中制备的双包层掺镱光纤主要性能指标已接近进口光纤。     

大模场面积掺镱微结构光纤的制备与激光性能（英文）

针对高功率光纤激光器在实际应用过程中所面临的高效耦合及激光输出质量问题,自行设计了大模场微结构光纤的波导结构,采用集束拉丝技术制备了纤芯直径41μm、内包层数值孔径0.62、纤芯数值孔径0.05、有效模场面积约530μm2的掺镱微结构光纤。在抽运功率为35.0 W的条件下,获得的单模激光输出功率为19.1 W,斜率效率为55.2%,光束质量因子M2小于1.01。     

百瓦级全光纤双包层光子晶体光纤放大器

利用双包层掺镱光子晶体光纤(DC-PCF)作为增益光纤,设计制作了全光纤双包层光子晶体光纤放大器。实验制作了匹配DC-PCF的(6+1)×1端面抽运耦合器,6根抽运光纤采用包层直径、纤芯直径分别为105μm和125μm(数值孔径为0.22)的多模光纤,信号光纤采用普通单模光纤。利用套管法制作端面抽运耦合器,并将制作完成的耦合器与DC-PCF直接熔接,再对光子晶体光纤进行锥棒熔接,锥棒输出端面镀1000~1100nm的增透膜,以防止激光反馈对整个放大系统产生影响。对全光纤双包层光子晶体光纤放大器进行测试,使用976nm的抽运源提供能量,信号光使用波长为1064nm、功率为2 W的连续光。当抽运功率达到最大值151.83 W时,最大输出功率为108.1 W,斜率效率为72.7%。输出光斑为很好的基模光斑,体现了光子晶体光纤在具有大模场面积的同时仍能保持基模传输的优良特性。     

多模与单模光纤级联系统对激光束的传输

分析了激光束在光纤中的非线性传输损耗,理论上证明了受激布里渊散射(SBS)是光纤传输能力的主要限制因素;实验上在532nm波段对长度为5m,纤芯半径为1.75μm,数值孔径(NA)为0.11的单模光纤的传输能力进行了测定,结果与理论一致。采用模场耦合理论,推导出多模光纤与单模光纤的直接耦合效率表达式,计算得到耦合效率与所选用的多模光纤和单模光纤的纤芯芯径之间的模拟关系。激光器输出波长为532nm;多模光纤的数值孔径为0.11,纤芯半径为12.5μm;单模光纤的数值孔径为0.11,纤芯半径为1.75μm,实验结果与理论基本吻合。根据理论和实验结果,设计出多模光纤与单模光纤混合传输方案,在柔性传输较高激光功率的同时可以得到高光束质量。     

基于1150 nm光纤激光抽运的中红外掺钬光纤激光器

采用1150nm光纤激光振荡器作为抽运源,实现了3μm波段中红外掺钬光纤激光器出光。该激光器采用线性谐振腔结构,其由镀金全反镜与切割角度为0°的光纤端面构成。增益介质为一段长为4.5m的双包层钬镨共掺氟化物光纤,纤芯直径为10μm,纤芯数值孔径为0.2。当1150nm抽运激光器功率为1.43W时,中红外掺钬光纤激光器输出功率为115mW,激光器系统的光-光转换效率为8.0%。在输出最大功率时,输出激光中心波长为2868.4nm,输出光谱的半峰全宽为1.3nm。相关研究成果对研制高功率紧凑型中红外掺钬光纤激光器具有一定的参考价值。     

低温下运行的光纤耦合激光二极管抽运 Tm,Ho:YLF激光器

为了实现小型化、高功率、高效率连续2μm激光输出，采用中心波长792nm激光二极管(LD)抽运双掺杂Tm．Ho：YLF晶体，将晶体封装在装有350mL液氮的杜瓦装置中．使其工作在77K温度条件下。光纤耦合激光二极管出纤功率14．8W．数值孔径0．3，芯径400μm。激光二极管端面抽运Tm，Ho：YLF激光器，产生2．05μm线偏振连续激光输出，最大功率5．2W。由于Tm^3-离子能级间的交叉弛豫效应导致的高抽运量子效率，实验获得的光-光转换效率为35％，斜度效率达到40％。采用双端面抽运结构．两个激光二极管注入功率29．6W时，Tm，Ho：YLF激光器输出功率达10．2W，相当于光光转换效率33％，斜度效率36％。     

掺Yb3+双包层石英光纤的研制及其激光特性

用MCVD工艺加溶液掺杂法研制成功了大几何尺寸、大数值孔径内包层的掺Yb3+双包层石英光纤,内包层直径125μm,数值孔径达0.36.完成了包层抽运光纤激光器的初步实验,在波长1.06μm处获得220mW的激光输出,光-光转换效率为26%.     

Interfacial reaction and shear strength of SnAgCu-xNi/Ni solder joints during aging at 150 °C

The interfacial microstructure and shear strength of Sn3.8Ag0.7Cu-xNi (SAC-xNi, x = 0.5, 1, and 2) composite solders on Ni/Au finished Cu pads were investigated in detail after aging at 150 °C for up to 1000 h. The interfacial characteristics of composite solder joints were affected significantly by the weight percentages of added Ni micro-particles and aging time. After aging for 200 h, the solder joints of SAC, SAC-0.5Ni and -1Ni presented duplex intermetallic compound (IMC) layers regardless of the initial interfacial structure on as-reflowed joints, whose upper and lower IMC layers were comprised of (CuNi)₆Sn₅ and (NiCu)₃Sn₄, respectively. Only a single (NiCu)₃Sn₄ IMC layer was ever observed at the SAC-2Ni/Ni interface on whole aging process. Based on the compositional analysis, the amount of Ni within the IMC regions increased as the proportion of Ni addition increased. The IMC (NiCu)₃Sn₄ layer thickness on the interface of SAC and SAC-0.5Ni grew more slowly when compared to that of SAC-1Ni and -2Ni, while for the (CuNi)₆Sn₅ layer the reverse is true. Except the IMCs sizes are increased with increased aging time, the interfacial IMCs tended to transfer their morphologies to polyhedra. In all composite joints testing, the shear strengths were approximately equal to non-composite joints. The fracturing observed during shear testing of composite joints occurred in the bulk solder, indicating that the SAC-xNi/Ni solder joints had a desirable joint reliability.     

有机发光二极管中ADN掺杂ErQ的1.54μm电致发光

自行设计了基于8-羟基喹啉铒(ErQ)为发射层(EMLs)和二硝酰胺铵(ADN)为蓝光主体材料的近红外有机发光二级管.器件的基本结构为(p-Si/NPB/EML/Bphen/Bphen:Cs2CO3/Sm/Au),设计并比较了三套不同发射层结构(ErQ/ADN为双层结构器件,(ErQ/ADN)×3为多层结构器件,ErQ:ADN为掺杂结构器件)的器件.三组器件在一定的偏压下,均可发出1.54μm的光,对应三价铒离子4I13/2→4I15/2的跃迁.其中,ADN:ErQ(1∶1)掺杂结构的近红外电致发光强度是ADN/ErQ双层结构中的三倍.此外,不同掺杂浓度的ADN:ErQ复合膜做了以下表征:吸收谱、光致发光谱和荧光寿命谱.实验结果证实了在近红外电致发光过程中存在从ADN主体分子到ErQ发射分子的高效率的能量转移.     

Emerging interconnects: a state-of-the-art review and emerging solutions

Aluminium was a primary material for interconnection in integrated circuits (ICs) since their inception. Later, copper was introduced as interconnect material which has better metallic conductivity and resistance to electromigration. As the aggressive technology scaling continues, the copper resistivity increased because of size effects, which causes increase in delay, power dissipation and electromigration. The need to reduce the resistor-capacitor??????? delay, dynamic power utilisation and the crosstalk commotion is as of now the fundamental main impetus behind the presentation of new materials. The purpose of this paper is to do a survey of interconnect material used in IC from introduction of ICs to till date. This paper studies and reviews new materials available for interconnect application which are optical interconnects, carbon nanotube (CNT), graphene nanoribbons (GNRs) and silicon nanowires which are alternatives to copper. While doing a survey of interconnect material, it is found that multiwalled CNTs, multilayer GNR and mixed CNT bundles are promising candidates and are ultimate choice that can strongly address the problems faced by copper but on integration basis copper would last for coming years.     

钠离子对poly(dT).poly(dA).poly(dT)三螺旋DNA分子呼吸模式的影响

利用分子结构的螺旋对称性,建立了一个包括钠离子的三链DNA分子poly(dT)*poly(dA)*poly(dT)的晶格动力学模型,计算了poly(dT)*poly(dA)*poly(dT)的氢键呼吸模式.结果发现钠离子的加入明显地淬灭了位于较低频率的几个最为强烈的Hoogensteen氢键呼吸模式,而对Watson-Crick氢键呼吸模式影响不明显,这说明钠离子能提高poly(dT)*poly(dA)*poly(dT)三螺旋结构的稳定性.该计算结果很好地解释了poly(dT)*poly(dA)*poly(dT)的热融化实验.     

聚对苯撑苯并双(口恶)唑发光及其器件制备

采用光谱技术,研究了聚对苯撑苯并双(口恶)唑(PBO)溶液的光敏发光特性,并用相对法估算出溶液发光效率在50%范围.结合光谱技术、半导体电学和电化学等研究手段,具体研究了以PBO为发光层的单层电致发光器件,研究结果显示,电致发光与薄膜的光致发光有具有相同的发光中心,峰值位于510 nm左右.同时发现,由于存制备过程中不同处理条件使得不同厚度薄膜残留的掺杂物质浓度不同,从而引起薄膜的导电性的不同.使得器件的阈值场强随PBO厚度的减小而逐渐增加.     

人小肠粘膜免疫酶的定位研究—光镜和电镜免疫组织化学染色法

本文对免疫酶组织化学的样品制备程序和染色方法做了详细的阐述。用直接法、间接法和ABC法,对人小肠免疫酶的定位,进行了光镜和电镜的观察,染色阳性反应显著,获得了满意的效果。并对染色技巧做了分析和探讨。     

BNBST无铅压电陶瓷的制备工艺研究

设计了（Bi0.55Na0.5）1-X（BaaSrb）xTiO3（BNBST[100x-100a／100b]）无铅压电陶瓷新体系。该体系压电陶瓷具有工艺特性及压电响应好，压电常数高的特点，且有实际应用前景的新型压电陶瓷材料体系。采用传统的陶瓷工艺制备了（Bi0.55Na0.5）1-X（BaaSrb）xTiO3无铅压电陶瓷，研究了制备工艺参数对其物化结构性能的影响。生料的热重-差热（TGA-DTA）分析表明，粉料合成过程中，先是SrTiO3、BaTiO3的形成，然后是（Bi0．5Na0．5）Tio，的形成，同时三者形成固溶体；密度测试表明，陶瓷的体积密度随烧结温度的升高而增大，可较易获得理论密度94％的陶瓷；X-射线能谱分析（EDAX）研究表明，陶瓷的Bi、Na的挥发随着烧结温度的升高而加剧。研究结果表明，要制备性能优良的无铅压电陶瓷，需要精确控制制备工艺。     

Arsenic deposition as a precursor layer on silicon (211) and (311) surfaces

We investigate the properties of arsenic (As) covered Si(211) and Si(311) surfaces by analyzing data from x-ray photoelectron spectroscopy (XPS) and low-energy electron diffraction (LEED) images. We then create a model using total surface energy calculations. It was found that both Si(211) and Si(311) had 0.68±0.08 surface As coverage. Si(211) had 0.28±0.04 Te coverage and Si(311) had 0.24±0.04 Te coverage. The Si(211) surface replaces the terrace and trench Si atoms with As for a lower surface energy, while the Si edge atoms form dimers. The Si(311) surface replaces all terrace atoms and adsorbs an As dimer every other edge site. These configurations imply an improvement in the mean migration path from the bare silicon surface by allowing the impinging atoms for the next epitaxial layer, tellurium (Te), to bind at every other pair of edge atoms, and not the step terrace sites. This would ensure a nonpolar, B-face growth.     

Joint estimation of TOA and DOA in IR-UWB system using a successive propagator method

Impulse radio ultra-wideband (IR-UWB) ranging and positioning require accurate estimation of time-of-arrival (TOA) and direction-of-arrival (DOA). With receiver of two antennas, both of the TOA and DOA parameters can be estimated via two-dimensional (2D) propagator method (PM), in which the 2D spectral peak searching, however, renders much higher computational complexity. This paper proposes a successive PM algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak searching. The proposed algorithm firstly gets the initial TOA estimates in the two antennas from the propagation matrix, then utilises successively one-dimensional (1D) local searches to achieve the estimation of TOAs in the two antennas, and finally obtains the DOA estimates via the difference in the TOAs between the two antennas. The proposed algorithm, which only requires 1D local searches, can avoid the high computational cost in 2D-PM algorithm. Furthermore, the proposed algorithm can obtain automatically paired parameters and has better joint TOA and DOA estimation performance than conventional PM algorithm, estimation of signal parameters via rotational invariance techniques algorithm and matrix pencil algorithm. Meanwhile, it has very close parameter estimation to that of 2D-PM algorithm. We have also derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer-Rao bound of TOA and DOA estimation in this paper. The simulation results verify the usefulness of the proposed algorithm.     

系统级封装新型埋入式电源滤波结构的研究

在高密度小尺寸的系统级封装(SiP)中,对供电系统的完整性要求越来越高,多芯片共用一个电源网路所产生的电压抖动除了会影响到芯片的正常工作,还会通过供电网路干扰到临近电路和其他敏感电路,导致芯片误动作,以及信号完整性和其他电磁干扰问题.这种电压抖动所占频带相当宽,几百MHz到几个GHz的中频电源噪声普通方法很难去除.结合埋入式电容和电源分割方法的特点,提出一种新型高性能埋入式电源低通滤波结构直接替代电源/地平面.研究表明,在0.65～4GHz的频带内隔离深度可达-40～75 dB,电源阻抗均在0.25ohm以下,实现了宽频高隔离度的高性能滤波作用.分别用电磁场和广义传输线两种仿真器模拟,高频等效电路模型分析这种低通滤波器的工作原理以及结构对隔离性能的影响,并进行了实验验证.