含单负介质层受阻全内反射结构的光子隧穿现象研究

利用稳定相位理论得到了光子穿越含单负介质层受阻全内反射结构的隧穿时间以及光子穿透光学势垒后产生的横向位移.分析结果表明，当势垒为单负介质时，光子隧穿可能表现出负的隧穿时间和负的横向位移.隧穿时间和横向位移存在Hartman效应，使得光子隧穿过程具有超光速性质.此外，基于TM波和TE波通过负介电常数介质和负磁导率介质势垒产生的横向位移的方向正好相反，得到了一种有效的区分两类单负介质的方法. 关键词： 光子隧穿 负折射 单负介质 超光速     

手征和运动介质界面异常光自旋霍尔效应

文章讨论了偏振高斯光束在空气-手征介质界面的反射和折射问题,发现了反射和折射光束的异常自旋霍尔效应.在某些特定的角度下,反射高斯光束重心的移动可以达到几十个波长的量级,通过调节手征参数,甚至会出现折射光重心移动方向由正到负的转变.文章还讨论了任意偏振高斯光束在空气-运动介质界面的反射和透射问题,当介质垂直于入射平面运动时,反射和透射光束的横向移动可以达到几个波长的量级,甚至在某些运动速度下可以实现移动方向正负的改变.这些研究对控制光的自旋霍尔效应提供了可能的途径.     

用于超快束匀滑的动态波前调控新方案

提出了利用光克尔效应实现激光束波前动态调控,进而实现焦斑超快束匀滑(ps量级)的方案,其原理是利用抽运光动态改变光克尔介质的折射率分布,以对透射主激光束附加时空耦合的动态波前,进而使激光束在靶面的焦斑散斑产生更加快速、多样的变化,最终实现焦斑的超快束匀滑.当抽运光时间波形为高斯脉冲序列,且以小角度倾斜入射至光克尔介质时,由于抽运光和光克尔介质对主激光附加随时间横向移动的周期性球面相位,且球面相位的幅值随时间不断变化,因而可以同步实现激光束焦面散斑的横向和径向超快速扫动,从而更为有效地改善靶面辐照均匀性.     

克尔型介质平板波导中的弱非线性横向电场波

对芯子为克尔型非线性介质、覆盖层和衬底为线性介质的平板波导，在弱非线性近似下，导出了这类波导横向电场波满足的色散方程和场分布，其物理意义清晰，且大大降低了数值计算的强度。     

线偏振光在手征负折射介质中的古斯汉欣位移特性研究

从理论上分析了手征负折射介质中的横向位移特性,给出了线极化波入射条件下发生全反射时的横向位移随入射角的关系曲线。当入射角处于两个本征波的临界角之间时,TE和TM分量对应的横向位移方向相反。而当入射角大于全内反射角时,两个分量都将朝着正方向发生横向位移。通过比较发现手征负折射介质中的古斯汉欣位移特性与常规介质和一般手征介质也有着很大的不同之处。     

各向异性有耗介质板介电系数和电导率的反演

简述了各向异性介质FDTD方法，并用FDTD方法分析了三维各向异性有耗介质板的瞬态后向散射.根据各向异性介质板后向散射与入射电磁波极化方向有关的特点，利用其后向RCS的谐振特性和后向散射场的时域波形特点反演有耗介质板的横向介电系数和电导率.数值模拟结果表明本反演方法可行，且方便、快捷. 关键词： 各向异性板 FDTD方法 有耗介质 谐振 反演     

横向各向同性均匀介质中格林张量的近似解

利用球座标系下的三重博里叶逆变换导出了均匀各向异性介质中具有横向各向同性性质一类介质的格林张量近似解，为研究属于这类介质的单向纤维增强复合材料和奥氏体钢等材料中声波的散射问题提供了理论基础。将所得的近似解与各向同性介质的情况作了比较，并进行了简单讨论。     

光在半无限厚多层矩形生物组织中的稳态漫射方程

传统的漫射方程均假设生物组织在纵向上是半无限厚的,横向上是无限大的。针对某些在横向上不是无限大的生物组织(如前臂和手指),建立了一个任意多层矩形生物组织漫射模型,该模型假设生物组织在纵向上是半无限厚的、多层的,在横向上是个矩形。在矩形边界条件下,根据光在生物介质中传播的漫射方程,结合外推边界条件,建立并给出了光在半无限厚稳态多层矩形介质中的漫射方程的精确解,利用建立的模型计算了空间分辨漫反射,同时编写相应的蒙特卡罗模拟程序,验证方程的正确性。建立的方程不但能解决横向上是矩形的介质问题,还能解决横向上无限大、纵向上半无限厚的介质问题,更能解决在横向上x或y轴之一是无限大、另一个轴是有限大小的组织问题。     

广义传播矩阵法分析分层各向异性材料对电磁波的反射与透射

在实验室坐标系下由Maxwell旋度方程出发构造了横向场的状态矢量和耦合矩阵,讨论了各 向异性介质中的特征波.通过引入横向场的传播矩阵,进而得到分层各向异性介质的反射系数和透射系数的解析表达式.该式可以适用于一般情况,包括分层单轴各向异性材料和回旋介质,以及半空间各向异性介质的反射和透射问题. 关键词： 广义传播矩阵 各向异性介质 反射与透射     

复折射率介质中的光导现象

讨论了激光在等效折射率横向分布为二次及高次型复折射率介质中的传输问题。数值计算结果表明，在二次及高次型介质中，无论是否考虑饱和效应，均存在特征距离，当激光传输距离大于特征距离后，将出现光导现象，其传输参数（光斑半径与曲率半径）只与介质有关。折射率的空间分布与增益的空间分布对光导的形成均有贡献。     

Transverse shift of the transmitted beam of anon-uniformly polarized paraxial light beam at dielectric interfaces

This paper reports that the central position of the reflected and transmitted beams of a nonlinear polarized light beam at the interface between two media undergoes transverse shifts. It presents a solution to the problem of transverse shift of a non-uniformly polarized paraxial light beam transmitting through interfaces between two homogeneous media by using a two-form amplitude and an extension matrix to represent the vector angular spectrum of a three-dimensional （3D） light beam. It derives general formula for the transverse shift of the transmitted beam, and discusses the shift of a well-collimated beam transmitting through an interface between two homogeneous media and a thin dielectric slab.     

Transverse Motion of Energy on Reflection and Refraction of Electromagnetic Waves

The equation of motion of the centre of energy of the reflected and refracted electromagnetic waves on the interface of dielectric media is obtained, it is shown that the physical reason leading to the transverse shift (TS) is the spin-momentum coupling of the electromagnetic waves near the interface.     

规范不变系统量子水平的变换性质及应用

按Faddeev-Popov路径积分量子化方法,给出规范不变系统在位形空间中的生成泛函,导出了系统位形空间中量子水平的变换性质.讨论了该系统量子水平的守恒律问题,且给出了Poincar群变换下电磁场在介质分界面附近量子水平的变换性质,在量子水平上说明了电磁波反射和折射时能量中心的“横移”现象. 关键词： 规范理论 位形空间 路径积分 “横移”效应     

任意偏振态光束全反射时的侧向和横向位移

光束在电介质界面发生全反射时,实际反射光束会在入射面内相对于几何反射光束产生一侧向位移,在垂直于入射面的方向产生一横向位移。利用改进的能流法研究了任意偏振态光束发生全反射时的侧向和横向位移特性。研究表明,侧向位移的大小与入射光束的两组成部分———TE和TM偏振光的相位差无关,而与两组分的光强比密切相关,且该位移可以表示为TE和TM偏振光束各自的位移按光强的加权平均。横向位移的大小不仅与入射光束两组分的光强比相关,还与组分的相位差密切相关。另外,反射光束不仅在椭圆偏振态入射的情况下会产生横向位移,而且在TE和TM偏振态之外的其他线偏振态入射时,也会产生横向位移。     

Surface Plasmon Polariton Fizeaus Dragging: via Relative Rotational Sensing

A new scheme focusing on the surface plasmon polariton interferometry between the metal and dielectric interface is introduced. The phase shift is measured by using surface plasmon polariton wave, generated at the interface of metallic and dielectric media. The phase shift of SPPs is modi?ed under phase and amplitude control of complex conductivity for interferometry. The control ?elds strongly in?uence the phase shift of SPPs for detection of molecular motion. The phase shift of SPPs is further modi?ed by Plasmon polariton Fizeaus dragging effect. We measure 20%–25%fractional change in delay and their phases shift between two left and right SPPs modes. Our results may have signi?cant applications in sensor interferometer technology.     

On the theory of dielectric relaxation

The Kirkwood expression for the static dielectric constant of a polar substance is extended to non-zero frequencies by a means which avoids the introduction of spherical specimens and the connection between the dipoledipole correlation functions of distinct spatial regions. The procedure is based on a previously derived relation between the dynamic dielectric constant and the current-current susceptibility and on the use of the Callen-Welton theorem to relate the susceptibility to fluctuations. Surface effects are eliminated at the outset by consideration of media which are infinite in extent. A general relation between the long-range dipole-dipole correlations (which fall off as the inverse cube of the distance) and short-range correlations in a specimen composed of non-polarizable molecules is found from a consistency relation. It is shown that the two microscopic relaxation times which result from the existence of but one relaxation time in the dielectric constant correspond to the transverse and longitudinal relaxation times with the longitudinal time being screened relative to the transverse time by the static dielectric constant.     

Analysis of Circular Dielectric Waveguide with Chiral Cladding

The propagation characteristics of a circular dielectric waveguide with chiral media filled in the cladding are investigated. The relation between the cutoff frequency and the chiral admittance, the dispersion curves for some modes with different angular mode numbers and the transverse distribution of fields are presented. Some new features different from the ordinary circular dielectric waveguide are resulted. The results show that the cladding chirality may lead to a single-mode operation in the circular dielectric waveguide.     

Transverse displacement at total reflection near the grazing angle: a way to discriminate between theories

The transverse shift is observed and precisely measured at total internal reflection on a dielectric interface for a circularly polarized light beam when the incident angle is scanned from the critical angle up to the grazing angle close to 90°. The experimental results show with no doubt that the transverse displacement exists far away from the critical angle and only vanishes at grazing angle. A comparison with theories also allows a discrimination between the most different theoretical models traditionally used to interpret physically this effect.     

Low-Frequency Stimulated Raman Scattering on Acoustic Vibrations of Dielectric Nanospheres in Aqueous Suspension

A low-frequency SRS (LFSRS) signal is detected at a certain dielectric nanoparticle (latex spheres) concentration in an aqueous suspension. The SRS line shift is close to its estimate by the “transverse” hypersound speed in latex.     

Optical absorption and energy-loss spectra of aligned carbon nanotubes

Optical-absorption cross-sections and energy-loss spectra of aligned multishell carbon nanotubes are investigated, on the basis of photonic band-structure calculations. A local graphite-like dielectric tensor is assigned to every point of the tubules, and the effective transverse dielectric function of the composite is computed by solving Maxwell's equations in media with tensor-like dielectric functions. A Maxwell-Garnett-like approach appropriate to the case of infinitely long anisotropic tubules is also developed. Our full calculations indicate that the experimentally measured macroscopic dielectric function of carbon nanotube materials is the result of a strong electromagnetic coupling between the tubes. An analysis of the electric-field pattern associated with this coupling is presented, showing that in the close-packed regime the incident radiation excites a very localized tangential surface plasmon. Received 18 January 2001