10.6μm波段光子晶体负折射现象的实验验证

介绍了10.6μm波段扫描负折射功率的实时探测系统,在实验上为探测光子晶体光频波段负折射现象提供了实验平台。该系统通过数据采集卡实现计算机对旋转台及平移台的控制,在以光子晶体样品为探测中心的轨道上,对折射光的整个空间功率分布进行实时采集和绘图。这一实验系统能够精确便捷地实现负折射现象在光频波段的探测。根据折射光最大光功率出现的位置,测得光束通过光子晶体样品的负折射现象,而且与理论结果基本吻合。     

超快太赫兹自旋光电子学研究进展（特邀）

太赫兹科学技术在光谱、成像、传感、生物医药、安全检测等方面展现出了巨大的应用潜力和价值。基于新材料和新机理,研发高效、超宽带和低成本的太赫兹光子学器件是太赫兹科学技术的重要挑战。近年来的研究表明,太赫兹光子学和超快自旋电子学深度交叉,获得了很大的关注。本文对超快太赫兹自旋光电子学所研究的物理机理和器件设计应用进行讨论。在物理机理研究方面,阐明了太赫兹脉冲为研究超快自旋电子学提供强大工具,实现了太赫兹驱动自旋波,探测自旋输运和超快磁测量。在器件设计与应用方面,介绍了基于自旋的新型太赫兹光子学器件,包括自旋太赫兹辐射源的优化方法,自旋太赫兹调制器的工作原理,自旋太赫兹探测器的设计方案。超快太赫兹自旋光电子学不仅有助于人们理解宏观自旋电子学现象背后的微观物理机制,而且有望实现高效的太赫兹光子学器件和光谱学应用。     

白光信息处理的现代进展

本文讨论了作者所提出的白光信息处理系统的基本概念,以及用它在进行复数滤波、信号综合及平行光学处理诸方面的若干研究成果。这种方法既消除了相干系统中不可避免的相干噪声,又保持了相干系统所具有的运算能力。值得指出的是,它还具有相干系统所不具有的独特优点,即由于光源本身的相当广阔范围的光谱分布,对多色信号及彩色图象的处理十分有利和相当有效。它为光学信息处理展示了一个新的具有良好前景的方向。     

对TiO2亲水特性有决定性影响的物理因素

影响TiO2薄膜亲水性的三种物理特性有——表面形貌、表面粗糙度、表面颗粒大小。本文中使用电子束蒸发法制备TiO2薄膜,使用AFM、静态接触角检测对不同厚度的TiO2薄膜的物理特性以及亲水特性进行了分析。结果显示,相较于薄膜表面的颗粒尺寸及表面粗糙度,薄膜表面形貌对TiO2薄膜亲水特性有着更重要的影响。     

基于二维光子晶体点缺陷可调谐光功率分配器

在二维矩形阵列结构硅光子晶体中去除中间一排硅柱形成线波导,在线波导右侧引入点缺陷。利用时域有限差分法(FDTD)模拟仿真以及数值分析研究线波导中光耦合特性,计算出两个通道的分光比,发现改变光子晶体的温度可以明显改变这两个通道的光功率比。基于此结构,提出了一种新的光功率分配器,可以获得大范围的光功率比值,从1∶1～90∶1都可以通过改变光子晶体的温度来实现,并且当温度从0℃～200℃就可以实现这一功能,最后设计了一款三通道可调谐光功率分配器,通过调节两个点缺陷区域内温度来实现光功率的分配。     

基于SPR的类铬型金属膜厚在线纳米测量研究

当具有足够大发散角的柱面光照射在匀厚金属薄膜表面时,由表面等离子体振荡产生的光反射率角分布是膜厚的函数,用CCD接收反射光分布信息并经过计算机分析处理,可实时、在线测量10nm内的铬、钛等金属膜厚,这类金属的复介电常数的实部相对虚部是较小的负数,故具有强反射锐峰及较平坦的吸收峰,该两峰点可作为膜厚测量依据的特征标记点,并通过建库进行曲线匹配而获得膜厚数值。实验结果表明,该方法的平均测量误差可低于0.4nm。     

基于维纳滤波的迭代盲解卷积

盲解卷积是在两个卷积因子未知的情况下,通过卷积结果来获知卷积因子的。不考虑噪声,针对高斯模糊图像,在初始估计点扩展函数之后,利用维纳滤波的方法进行频域迭代盲解卷积,达到图像恢复的目的。实验表明,恢复的图像纹理比较清晰,边缘有所改善,主观视觉效果显著。该算法提高了分辨率。     

Local Lattice Distortion Around VPb^2- in PbWO4 and the Origin of the 420nm Luminescence Band

The lattice structures around one lead vacancy VPb^2- in PbWO4 are studied within the framework of the fullrelativistic density functional theory. Using the conjugate gradient method, we optimize the geometry of the ions around VPb^2- by moving the ions within the sub-cell until specified tolerance is satisfied. We obtain the geometric positions of ions around VPb^2- after optimization. The calculated results indicate that there would be local lattice distortion caused by the existence of VPb^2-. The electronic structures of both the optimized and pre-optimized PWO containing VPb^2- have been calculated. The density of states of the distorted PWO indicates that the energy gap between the 2p state of O^2- and the 5d state of W^6 is 3.90eV, which shows that the distorted W-O tetrahedron may be the 42Onm luminescence centre.     

Study on forward stimulated Brillouin scattering in a backward pumped fiber Raman amplifier

Strong multi-order forward stimulated Brillouin scattering (SBS) has been observed in the backward pumped S-band distributed fiber Raman amplifier (FRA) with tunable narrow signal source (less than 100 MHz) when the pump power of FRA reached the SBS threshold. This does not obey the theory that only weak backward SBS lines exist according to the conservation of energy and momentum and the wave vector selected rule. This is because the sound waveguide characteristic weakens the wave vector rule, and the forward transmitted sound waveguide Brillouin scattering lines are generated and amplified in FRA.When the pump power is further increased, 11 orders of SBS lines and comb-like profile are observed. For the excited line, the frequency is 197.2296 THz and the power is 0 dBm. The even order SBS lines are stronger than odd order SBS lines, the power of the 2nd and 4th order SBS lines is 1.75 dBm, which is 16 dB higher than that of the 1st and 3rd order SBS lines. The odd order SBS lines are named BrillouinRayleigh scattering lines.     

First-Principles Studies on the Electronic Structures and Optical Properties for the PbWO4 Crystal Containing V^2-pb

The electronic structures, dielectric functions, complex refractive indices and absorption spectra for a perfect PbW04 (PWO) crystal and the PWO crystals containing lead vacancy V^2-pb have been calculated using a full-potential (linearized) augmented plane-wave (LAPW) local orbitals (LO) method with the lattice structureoptimized. The peaks of the absorption spectra corresponding to the electronic transitions have been studied.