基于VO2相变的光控太赫兹调制器

基于VO2薄膜相变特性,通过在石英基底上制备VO2薄膜和亚波长金孔阵列,并在理论和实验上研究了金属孔阵列与VO2薄膜置于基底同侧和异侧的两种太赫兹(THz)调制器。系统研究了在光泵浦条件下两种样品的THz波的传输特性。结果表明,随着泵浦光功率的改变,两种结构的器件均可以实现对THz波强度的调制。对比分析两种结构器件的THz透射谱发现,紧邻金属孔阵列的金属相VO2能够有效地抑制THz表面等离子体的局域透射增强效应,使调制器的调制深度得到显著增强,这对基于相变材料调制器的设计具有重要意义。     

一种以太网介质访问控制器芯片的设计与实现

完成了10/100(Mb/s)以太网介质访问控制器芯片的设计与实现,介绍了芯片的架构和主要模块的设计方法,给出了仿真结果.芯片采用0.25μm CMOS工艺流片,工作电压为2.5 V/3.3 V.测试表明,芯片性能完全符合IEEE802.3标准,达到了设计要求.     

用于手写体数字不变性特征提取及识别的自组织算法

针对无约束手写体数字的特点,本文提出了一种用于手写体数字特征提取和识别的神经网络与视觉学习相结合的自织织学习算法,为了避免网络规模太大引起"过度训练"现象而导致网络的推广能力下降,提出了一种在学习过程中自适应删剪不重要权重的方法.计算机模拟结果显示该算法能有效地提取手写体数字的不变性特征,进而提高对无约束手写体的识别率.     

高斯光束入射折射率失配对共焦显微术的影响

采用光的矢量衍射理论，研究了场振幅为高斯分布的平面波入射到无球差高数值孔径物镜上，折射率失配对共焦显微术的影响，并进行数值模拟。结果表明，在折射率失配情况下，点扩散函数在xz平面上的分布相对于焦平面不再为对称分布，同时出现焦点漂移、半高宽变宽的现象。     

Distinguish on the viability of human umbilical cord mesenchymal stem cells using delayed luminescence

In this paper, we report the discrimination of the viability of human umbilical cord mesenchymal stem cells (hUC-MSCs) with photo-induced delayed luminescence (DL). We measure the DL decay kinetics of hUC-MSCs using an ultraweak luminescence detection system, and find the significant difference in the weight distributions of the decay rate for hUC-MSCs with high and low viabilities. Spectral discrimination of hUC-MSCs with high and low viabilities is thus carried out by comparing the DL kinetics parameters, including the initial intensity, the peak decay rate and the peak weight value. Our results show that the novel optical method for the viability diagnosis of hUC-MSCs has a promising prospect.     

A metamaterial terahertz modulator based on complementary planar double-split-ring resonator

A metamaterial based on complementary planar double-split-ring resonator (DSRR) structure is presented and demonstrated, which can optically tune the transmission of the terahertz (THz) wave. Unlike the traditional DSRR metamaterials, the DSRR discussed in this paper consists of two split rings connected by two bridges. Numerical simulations with the finite-difference time-domain (FDTD) method reveal that the transmission spectra of the original and the complementary metamaterials are both in good agreement with Babinet’s principle. Then by increasing the carrier density of the intrinsic GaAs substrate, the magnetic response of the complementary special DSRR metamaterial can be weakened or even turned off. This metamaterial structure is promised to be a narrow-band THz modulator with response time of several nanoseconds.     

Sn doped ZnO thin films as high resistivity window layer for Cu(In,Ga)Se2 solar cells

For high efficiency Cu(In,Ga)Se2 (CIGS) solar cell, the high-resistivity layer with high optical transmittance has to be adopted between the buffer layer and the high-conductivity window layer. In this paper, we propose Sn doped ZnO (ZTO) film, instead of the traditional intrinsic ZnO (i-ZnO) film, as an alternative n-type high-resistivity window layer for CIGS solar cell. In this experiment, both ZTO and i-ZnO films are strong (002) oriented, and the surface morphologies of the two films are almost the same. The statistical roughnesses of i-ZnO film and ZTO film are 0.58 nm and 0.63 nm, respectively. However, the optical transmittance of ZTO film is higher than that of i-ZnO film with the same thickness. The efficiency of ZTO based CIGS cell was 14.24%, which is almost the same as the efficiency of i-ZnO based CIGS cell. These results fully suggest that it is very feasible to replace i-ZnO with ZTO as the high resistant window layer.