扩展BANYAN网络的可重构 无阻塞8×8矩阵光开关

在分析CROSSBAR网络(CN)和BANYAN网络(BN)结构的基础上,提出了一种新的扩展BANYAN网络(EBN)可重构无阻塞结构。以8×8矩阵光开关为例,分析了EBN结构的两种形式及其可重构无阻塞特性,给出了开关单元驱动逻辑。从理论上计算了SiO₂波导EBN结构矩阵光开关的光学损耗和功耗。对于8×8开关,插入损耗为3.3 dB。按理论计算设计制作了8×8矩阵光开关,测得波导传输损耗为0.1 dB/cm,光纤-波导耦合损耗为0.5 dB/point。光开关插入损耗为4.6 dB,平均串扰为-38 dB,平均偏振相关损耗为0.4 dB,开关平均功率为1.6 W,响应时间约为1 ms。实验结果与理论计算基本符合。     

基于MEMS开关的双频可重构天线设计

本文设计了一个工作于Ka频段的双频可重构微带缝隙天线.该可重构天线使用RF-MEMS开关来实现24GHz和30GHz两个工作频率之间的切换,且在这两个工作频率上都具有相同的输入阻抗、极化方向和辐射方向图.本文给出了天线的设计流程,最后仿真得到的结果与期望结果一致,达到了一般天线设计要求,可适用于多系统集成化应用中.     

HCl-（NH4）2S2O8体系抛光液中钌的化学机械抛光研究

金属钌(Ru)有可能作为集成电路中铜互连阻挡层材料,作为阻挡层必须具有低的表面粗糙度。化学机械抛光技术已经成为集成电路制造中实现局部平面化和全局平面化的关键技术,因此对钌的化学机械抛光研究具有重要意义。利用自制抛光液,研究了在HCl-(NH4)2S2O8体系抛光液中盐(KCl)的浓度、络合剂浓度、pH值和抑制剂(BTA)等对钌的去除速率的影响。实验发现,在HCl-(NH4)2S2O8体系抛光液中,金属钌在1wt.%SiO2、1wt.%过硫酸铵、1wt.%酒石酸、1mmol/L BTA和10mmol/L KCl,pH值为9.0的抛光液中,抛光速率为10.8nm/min。电化学实验发现,在1wt.%SiO2、1wt.%过硫酸铵、1wt.%酒石酸、1mmol/L BTA和1mmol/L KCl,pH值为4.0的抛光液中,金属钌表面化学反应受抑制;在1wt.%SiO2、1wt.%过硫酸铵、1wt.%酒石酸、1mmol/L BTA和1 mmol/L KCl,pH值为9.0的抛光液中,金属钌表面钝化膜较致密、较厚。     

基于双通道M-Z干涉仪的FBG光开关研究

为降低电光开光的插入损耗并提高性能,提出了一种基于双通道可调谐马赫-曾德(M-Z)干涉仪制作的光纤布拉格光栅(fiber Bragg grating,简称FBG)光开关,通过改变干涉仪中的可调电动光纤延迟线的延迟时间,实现滤波谱周期的可调谐。通过改变干涉仪其中一臂的延迟时间设定,该光开关能够实现对设定波长光波的开关功能。对光纤M-Z干涉滤波原理进行了理论分析,使用C波段宽带放大自发辐射光源对双通道可调M-Z干涉仪的性能进行了测试。结果表明,其可实现大范围及高精度的滤波调节功能。对基于双通道可调谐马赫-曾德干涉仪制作的FBG光开关,通过FBG开关性能检测系统实验,得到该光开关在波长为1 550nm处的输出光谱,光开关的消光比达到25dB。结果表明,该光开关能够实现大范围高精度滤波功能,具有高消光比、结构简单和易于调节等优点。     

Al2O3-TiB2-ZrO2三元复合陶瓷刀具的性能研究

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基于Simulink的开关磁阻电动机/发电机一体化仿真

开关磁阻电机由于功率变换器的结构所特有的允许能量双向传输性,使其很适合于作为电动机／发电机一体机使用本文基于Matlab/Simulink建立了一个开关磁阻电动机／发电机一体化的开放平台,在此平台上可以进行各类控制策略,新型模型的研究和仿真。     

基于梯度结构的Al2O3/ZrO2陶瓷刀具材料的制备及其力学性能

采用真空热压烧结方式制备了Al₂O₃/ZrO₂梯度复合陶瓷刀具材料,并对ZrO₂含量及梯度结构层厚比进行了优化。层厚比为2.0的AZE20梯度复合陶瓷刀具材料维氏硬度为(18.7±0.33) GPa,抗弯强度为(937±28.5) MPa,断裂韧性为(8.2±0.32) MPa·m^1/2,相比最佳ZrO₂含量的均质复合陶瓷刀具材料AZ20,维氏硬度、抗弯强度和断裂韧性分别增加了22%、37.8%和43.8%。梯度结构的设计使表层形成残余压应力,晶粒得到一定程度的细化,更多的ZrO₂晶粒因残余压应力尺寸稳定在t相ZrO₂晶粒尺寸。在复合材料断口形貌中发现,其断裂方式为表层穿晶断裂和中间层沿晶断裂的结合,这种混合断裂方式使刀具整体力学性能得到提高。     

基于Fe3O4/SiO2/Au-MNPs磁性SERS基底的特布他林超灵敏检测

为了快速灵敏地检测特布他林(terbutaline,TB),制备核?卫星纳米结构的Fe3O4/SiO2/Au-MNPs磁性基底对其进行表面增强拉曼光谱(SERS)检测。通过磁性分离、调节体系pH的方法考察特布他林浓度与拉曼光谱强度之间的线性关系并绘制校准曲线。实验结果表明,该纳米卫星结构的磁性SERS基底对TB的检测限为3.77×10^?10 mol/L,同时在5×10?5~5×10^?9 mol/L范围内,TB的SERS信号与其浓度呈线性关系,利用最小二乘法拟合得到的线性相关系数R2为0.996。该复合材料制备方法简便易行,为合成其他纳米复合材料提供了参考。     

基于CO2激光单点加热的微泡腔制备及其性能研究

为了简化微泡腔的制备工艺,在传统CO_2激光双向加热方案的基础上,采用CO_2激光单点加热毛细管。通过精确控制加热温度和气体流速,制备出半球形的微泡腔,进而通过调节激光光斑,增加加热面积的方式制备出球形的微泡腔。使用光学显微镜和原子力显微镜(AFM)对制备的球形微泡腔进行表征,并通过COMSOL仿真验证了所制备微泡腔的性能。所制备的微泡腔表面光滑,壁厚最薄处可达到亚微米量级。研究结果表明,通过CO_2激光单点加热制备的微泡腔的壁厚存在轻微的不均匀性,但其谐振Q值仍然较高,可广泛应用于传感领域。     

基于Matlab/Simulink的开关磁阻电动机仿真分析

由于开关磁阻电动机结构与运行原理的特殊性,使其分析和设计较其他电动机文章更为困难。基于开关磁阻电动机的准线性动态模型,利用Matalab／simulink,对开关磁阻电动机建模。此模型通用性强,修改方便,在该模型基础上进行了开关磁阻电动机调速系统的仿真。仿真结果如实地反映了SRD的工作状况。     

Characterization of nanoscale recording mark on Ge2Sb2Te5 film

We have fabricated nanoscale recording marks on Ge₂Sb₂Te₅ (GST) films with conductive atomic force microscope (AFM). GST films were deposited on glass or polyimide film with thickness of 150–200 nm by the rf–sputtering method. Through current–voltage (I–V) spectroscopy, good cantilevers for fabrication and characterization of nanoscale marks on GST were selected. A fresh and highly conductive tip showed voltage-switching characteristic in the I–V curve, where the threshold voltage was 1.6 V. Nanoscale dot and wire arrays of crystalline phases were successfully obtained by varying sample bias voltage from −10 to 10 V. With highly conductive tips, nanowires having full-width at half-maximum of 20 nm could be fabricated, whereas nanowires could not be fabricated with bias voltage below −2 V. The width of the nanoscale mark was increased by repetition of AFM lithography even with same applied voltage and lithography speed. For a thicker nanowire, the width measured in current-image (C-image) was observed to be 2 times of that measured in topography-image (T-image). This result supports that current sensing provides an image of phase-changed GST area with higher resolution than topography sensing.     

基于CO2激光的微纳光纤熔接技术研究

为了解决微纳光纤之间的结构稳定性差的问题,使用CO_2激光作为加热源,加热两根重叠在一起的微纳光纤,并在显微镜下观察其熔接情况,最终将两根微纳光纤熔接成一根,而且熔接点的光纤表面光滑,直径均匀。通过CO_2激光加热的方法,实现了微纳光纤高质量的熔接,增加了微纳光纤之间的机械稳定性,使其更容易制作出纳米光子器件。     

Numerical studies of optical switching and optical bistability phenomena of nano- or meso-size spheres

We propose the use of numerical calculations of the optical response of nonlinear Kerr‐spheres, modifying the Mie theory. As a numerical example, we use a CuCl sphere coated with a Kerr‐nonlinear sphere, taking into account the excitation of the Z₃‐exciton. The results clearly show that optical bistable and/or optical switching devices can be realized on a nano‐ and meso‐size scale when the real part of the dielectric constant of CuCl is negative.     

Spectroscopic scanning near-field optical microscopy with a free electron laser: CH2 bond imaging in diamond films

Hydrogen chemistry in thin films and biological systems is one of the most difficult experimental problems in today's science and technology. We successfully tested a novel solution, based on the spectroscopic version of scanning near-field optical microscopy (SNOM). The tunable infrared radiation of the Vanderbilt free electron laser enabled us to reveal clearly hydrogen-decorated grain boundaries on nominally hydrogen-free diamond films. The images were obtained by SNOM detection of reflected 3.5 µm photons, corresponding to the C–H stretch absorption, and reached a lateral resolution of 0.2 µm, well below the λ/2 (λ= wavelength) limit of classical microscopy.     

Thermal sensors based on p-Pb0.925Yb0.075Te:Te and n-Pb0.925Yb0.075Se0.2Te0.8 thin films grown using thermal evaporation method

We utilize p-Pb_0.925Yb_0.075Te:Te and n-Pb_0.925Yb_0.075Se_0.2Te_0.8 ingots in a standard solid-state microwave synthesis route to fabricate thermally evaporated thin films. The nanostructure and composition of the films were studied through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). The Seebeck coefficient and electrical conductivity were measured at a temperature range of 298–523 K. The micro-thermoelectric devices were composed of 20 pairs and 10 pairs of p-Pb_0.925Yb_0.075Te:Te and n-Pb_0.925Yb_0.075Se_0.2Te_0.8 thin films on glass substrates, respectively. The dimensions of the thin films thermoelectric generators which comprised of 10-pair were 12 mm × 10 mm, whereas, 20-pair were 23 mm × 20 mm, respectively of legs connected through aluminum electrodes. The serial 20-pair p–n thermocouples generated a maximum output open-circuit voltage of 275.3 mV and a maximum output power of 54.37 nW at a temperature difference of ΔT = 162 K; the values are 109.4 mV and 16.68 nW at ΔT = 162 K for the 10-pair thermocouples, respectively.     

基于光线追踪法的高精度CO2测量系统的研究

为了提高测量精度,对光线的有效利用率和最佳光程的选择进行了推导和优化。首先应用光线追踪法模拟CO2气室光路结构,计算光线的有效利用率;其次通过分析红外探测器接收到的光线,计算光程长对测量结果贡献率的影响,得出4.26μm波长下CO2的最佳光程为31mm。据此设计了CO2体积分数测量系统,并对20×10-6~1 500×10-6范围内的标准气体进行了测量。实验结果表明,该系统的测量精度可达到50×10-6。     

Characterization and fabrication of fully metal-coated scanning near-field optical microscopy SiO2 tips

The fabrication of silicon cantilever‐based scanning near‐field optical microscope probes with fully aluminium‐coated quartz tips was optimized to increase production yield. Different cantilever designs for dynamic‐ and contact‐mode force feedback were implemented. Light transmission through the tips was investigated experimentally in terms of the metal coating and the tip cone‐angle. We found that transmittance varies with the skin depth of the metal coating and is inverse to the cone angle, meaning that slender tips showed higher transmission. Near‐field optical images of individual fluorescing molecules showed a resolution < 100 nm. Scanning electron microscopy images of tips before and after scanning near‐field optical microscope imaging, and transmission electron microscopy analysis of tips before and after illumination, together with measurements performed with a miniaturized thermocouple showed no evidence of mechanical defect or orifice formation by thermal effects.     

单层MoS2和WS2的太赫兹近场显微成像研究

采用太赫兹散射式扫描近场光学显微镜(THz s-SNOM)研究了化学气相沉积法制备的单层MoS₂和WS₂晶粒的太赫兹近场响应。在没有可见光激发时,未探测到可分辨的太赫兹近场响应,说明晶粒具有较低的掺杂载流子浓度。有可见光激发时,由于光生载流子的太赫兹近场响应,能够测得与晶粒轮廓完全吻合的太赫兹近场显微图。在相同的光激发条件下,MoS₂的太赫兹近场响应强于WS₂,反映了两者之间载流子浓度或迁移率的差异。研究结果表明,THz s-SNOM兼具超高的空间分辨率和对光生载流子的灵敏探测能力,对二维半导体材料和器件光电特性的微观机理研究具有独特的优势。