对2014年高考重庆卷第5题的进一步解析

文章对2014年全国高考重庆卷第5题进行了定量研究。     

Optical absorption tunability and local electric field distribution of gold-dielectric-silver three-layered cylindrical nanotube

The effects of inner nanowire radius, shell thickness, the dielectric functions of middle layer and surrounding medium on localized surface plasmon resonance (LSPR) of gold-dielectric-silver nanotube are studied based on the quasi-static approximation. Theoretical calculation results show that LSPR of gold-dielectric-silver nanotube and LSPR numbers can be well optimized by adjusting its geometrical parameters. The longer wavelength of $\left|\omega_{-}^{-}\right\rangle$ mode takes place a distinct red-shift with increasing the inner nanowire radius and the thickness of middle dielectric layer, while a blue-shift with increasing outer nanotube thickness. The physical mechanisms are explained based on the plasmon hybridization theory, induced charges and phase retardation. In addition, the effects of middle dielectric function and surrounding medium on LSPR, and the local electric field factor are also reported. Our study provides the potential applications of gold-dielectric-silver nanotube in biological tissues, sensor and related regions.     

一种有效电磁场散射数值计算方法

文章主要介绍了一种有效的电磁场数值模拟计算方法,详细讨论了其针对均匀无限大和有界空间问题时快速算法的实现,与没有采用快速算法进行比较,数值结果表明,采用快速算法能有效地节约计算机内存,提高运算效率。最后数值模拟了样品的电磁散射并对结果进行了分析。     

电磁波极化的判别方法及MATLAB呈现

文章介绍电磁波极化的概念和左旋、右旋极化波的判别方法。线性极化需满足条件"两相位相差0或π",圆极化波为"两振幅相等且相位差为π2",其他情形为椭圆极化波。通过两个方向即电场旋转方向与波传播方向来判别左旋与右旋极化波,同时利用MATLAB实现电场强度的轨迹可视化、形象化,加深学生对极化概念的进一步理解,有效提高了教学效果。     

Theoretical Studies of Optical Properties of Silver Nanoparticles

Optical properties of silver nanoparticles such as extinction, absorption and scattering efficiencies are studied based on Green＇s function theory. The numerical simulation results show that optical properties of silver nanoparticles are mainly dependent on their sizes and geometries; the localized plasmon resonance peak is red shifted when the dielectric constant of the particle＇s surrounding medium increases or when a substrate is presented. The influences of wave polarizations, the incident angles of light, the composite silver and multiply-layers on the plasmon resonance are also reported. The numerical simulation of optical spectra is a very useful tool for nanoparticle growth and characterization.     

核/壳型纳米银球的局域表面等离子体共振调谐特性研究

利用离散偶极子理论数值模拟了核/壳结构纳米银球局域表面等离子体共振调谐特性,并应用等离子体杂化理论对其数值结果进行了解释。研究结果表明:对于固定的球壳结构,当改变内核介质的介电常数与内核结构尺寸时,其等离子体共振峰发生了明显的移动现象;对于固定的内核结构,当外核厚度变化时能有效实现共振峰的调控。     

Optical Tunability of Silver-Dielectric-Silver Multi-Layered Cylindrical Nanotubes Using Quasi-Static Approximation

Local surface plasmon resonances(LSPRs) of silver-dielectric-silver multi-layered(SDS-ML) nanotubes are studied by theoretical calculations. Based on quasi-static approximation, the absorption cross section of SDS-ML nanotubes is plotted as a function of wavelength. The results show that SDS-ML nanotubes exhibit strong coupling between the cylindrical silver and nanotubes. The absorption spectra of LSPRs are strongly influenced by changing the radius of the inner core and outer nanotube shell. The longer wavelength is red-shifted by increasing the radius of the inner core and outer shell, while the short wavelength shows the opposite properties.These phenomena are explained by the plasmon hybridization theory. In addition, for clarity, the distributions of electric field intensity at their plasmon resonance wavelengths are also studied.     

"通信原理"易混淆知识点浅析

"通信原理"是电子信息类专业课程中的一门重要课程。本文通过图文结合的方式将"通信原理"教学中学生容易混淆的9对知识点逐一进行比较分析,阐述彼此之间的区别和联系。通过对带通滤波与低通滤波等9对知识点的讨论,引导学生理解这些知识点在通信系统中的作用,提高学生学习"通信原理"的兴趣和积极性。