十二重准晶中的方向缺陷

采用多重散射的方法研究了十二重准晶中的缺陷模,发现在十二重准晶中存在方向缺陷,且当缺陷组合围绕对称中心旋转时,在保持原有缺陷模的基础上,出现了新的缺陷模. 关键词： 准晶 缺陷 带隙     

Manipulation of plasmonic wavefront and light–matter interaction in metallic nanostructures: A brief review

The control and application of surface plasmons （SPs）, is introduced with particular emphasis on the manipulation of the plasmonic wavefront and light-matter interaction in metallic nanostructures. We introduce a direct design methodology called the surface wave holography method and show that it can be readily employed for wave-front shaping of near-infrared light through a subwavelength hole, it can also be used for designing holographic plasmonic lenses for SPs with complex wavefronts in the visible band. We also discuss several issues of light-matter interaction in plasmonic nanostructures. We show theoretically that amplification of SPs can be achieved in metal nanoparticles incorporated with gain media, leading to a giant reduction of surface plasmon resonance linewidth and enhancement of local electric field intensity. We present an all-analytical semiclassical theory to evaluate spaser performance in a plasmonic nanocavity incorporated with gain media described by the four-level atomic model. We experimentally demonstrate amplified spontaneous emission of SP polaritons and their amplification at the interface between a silver film and a polymer film doped with dye molecules. We discuss various aspects of microscopic and macroscopic manipulation of fluorescent radiation from gold nanorod hybrid structures in a system of either a single nanoparticle or an aligned group of nanoparticles. The findings reported and reviewed here could help others explore various approaches and schemes to manipulate plasmonic wavefront and light-matter interaction in metallic nanostructures for potential applications, such as optical displays, information integration, and energy harvesting technologies.     

Influence of tip geometry on the spatial resolution of tip enhanced Raman mapping

In 2013,a breakthrough experiment pushed the Raman mapping of molecules via the tip-enhanced Raman scattering(TERS) technique to a sub-nanometer spatial resolution,going into the single-molecule level.This surprising result was well explained by accounting for the critical role of elastic molecule Rayleigh scattering within a plasmonic nanogap in enhancing both the localization and the intensity level of the Raman scattering signal.In this paper,we theoretically explore the influence of various geometric factors of the TERS system on the spatial resolution of Raman mapping,such as the tip curvature radius,tip conical angle,tip–substrate distance,and tip–molecule vertical distance.This investigation can help to find out the most critical geometric factor influencing the spatial resolution of TERS and march along in the right direction for further improving the performance of the TERS system.     

银河系中心超大质量黑洞的探索历程

经过逾半个世纪的探索,天文学家确认在我们银河系的中心存在一个4百万倍太阳质量的致密天体,很可能是爱因斯坦广义相对论所预言的黑洞。文章简要回顾了探索这个大质量致密天体过程中的若干里程碑。     

部分空气桥式硅膜二维光子晶体

描述在Si基底上制备带隙在近红外波段部分空气桥式二维光子晶体（PC）.选用HF酸溶液作为腐蚀液，利用聚焦离子束刻蚀技术直接刻蚀出具有三角形空气洞结构的二维PC，并测出了二维PC完整的第一带隙透过谱的带隙范围为123—155μm.实验测得的透过谱与理论计算的空气桥式二维PC的计算结果一致.类TM0模的存在减小了带隙的宽度.由于部分SiO2支撑桥式平板，二维PC易于按所需尺寸进行制备.同时，通过改变平板下的支撑材料，可以制出有源的PC，利用这种机理可以把光从支撑材料中引出. 关键词： 二维光子晶体 带隙 平板波导     

水中脉冲放电金属电极烧蚀机理

采用板-板电极, 在放电间隙距离为2 mm、放电电流峰值为22 kA条件下, 对黄铜、钨铜电极的烧蚀特性进行了对比研究。利用高精度天平测量放电过程中的电极质量损失, 分别获取了阴极、阳极及总的平均烧蚀速率。通过放电后电极表面微观形貌、微观元素组成的分析及液体中金属离子的含量分析, 对水中脉冲放电金属电极的烧蚀机理进行了探讨。结果表明, 水中脉冲放电时, 钨铜电极的抗烧蚀性能明显高于黄铜电极。黄铜电极的主要烧蚀是以中心的大量孔洞及其边缘的波纹结构为表现形式的液体金属的溅射;钨铜电极的突出物及较平整的表面暗示了气相侵蚀的作用。以电弧的焦耳热效应为催化剂, 钨铜与水的电化学反应更为强烈, 因此电化学腐蚀是水中放电电极烧蚀的形式之一。     

集成微光机电系统中的矢量光学问题

集成微光机电(MOEM) 系统是近年来迅速地发展起来的一门新兴的综合学科,它融合了微光学元件、微电子器件和微机械结构的优点.不但在技术上有重要的应用,还蕴涵着与小尺寸器件有关的力学、热学、电学、光学,以及材料科学等丰富的基础科学研究课题.文章探讨了MOEM 系统中典型的微光学元件,如衍射微透镜、折射微透镜和微光栅中的矢量光学问题,简要地介绍了相应的求解方法.     

高铁酸盐制备,性质及应用

本文概括了高铁酸盐方面的主要研究成果。对高铁酸盐制备及性质作了介绍,论述了其在化学工业及环境工程方面应用的可能性与优越性。     

二维各向异性光子晶体完全带隙的增宽

介绍了光子晶体能带设计的一种新机制,利用各向异性材料制作二维光子晶体,可以大大提高光子晶体的完全带隙宽度。     

应用于宽带中红外激光产生的啁啾周期极化铌酸锂晶体结构设计及数值模拟

中红外波段3—5μm激光光源在医疗、基础科学、通信、工业等众多领域都有着重要的应用需求,而受制于中红外波段的增益介质,传统的激光产生及放大的方法如再生放大、多程放大、行波放大等已经不适用.为了产生宽带且高能量的中红外激光,本文结合准相位匹配技术和啁啾周期极化铌酸锂(CPPLN)晶体进行了理论分析.通过计算分析铌酸锂晶体的色散关系曲线,对CPPLN晶体的结构参数进行设计和调节.结合非线性耦合波方程组与四阶龙格库塔法对该晶体在800 nm激光的抽运下,与0.95—1.6μm范围内的信号光进行准相位匹配差频转换进行了数值模拟.研究表明,在单块CPPLN晶体中,结合准相位匹配技术,能够高效产生覆盖1.6—5μm的中红外激光.对CPPLN晶体产生中红外激光的理论分析和数值模拟,能够为进一步的实验探究等提供方案参考和理论支持.