一维光子晶体材料中的光学传输特性

研究了光在一维周期性介电材料中的传播特性,指出传统的高反膜只是光子晶体的一个特例,从而从光子晶体的角度对多层膜系的设计提出了一条新的思路,同时研究了材料的介电常数以及结构与高反带带宽之间的关系。最后通过在多层膜中引入掺杂（中间一层被另一种介质所代替）,得到第一能隙中掺杂模式的频率与掺杂材料的介电常数之间的对应关系,由此提出一种精确测量介质介电常数的方法。     

Large Positive and Negative Lateral Displacements from Total Internal Reflection Configuration with a Weakly Absorbing Dielectric Film

It is theoretically shown that the simultaneously large positive and negative lateral displacements will appear when the resonant condition is satisfied for a TE-polarized light beam reflected from the total internal reflection configuration with a weakly absorbing dielectric film. Appearance of the enhanced negative lateral displacement is relative to the incidence angle, absorption of the thin film and its thickness. If we select an appropriate weakly absorbing dielectric film and its thickness, the simultaneously enhanced positive and negative lateral displacements will appear at different resonant angles. These phenomena may lead to convenient measurements and interesting applications in optical devices.     

Light Propagation in an Inhomogeneously Absorbing Medium: Near Field of GaAs-Light Emitting Diodes

The light propagation in media with inhomogeneous absorption is investigated by solving the wave equation in the approximation of very short wavelengths. The lowest order correction of the straight-on light propagation is given. In the approximation of light rays the near-field intensity of a light emitting diode (LED) is calculated by using a special absorption function within the region of light excitation.     

Propagation Rule of Pulsed Light Beams through First-order Optical Systems

1.IntroductionInthepastfe\\'ycarsltllcil1tcnsity-momentsmethodandtheM2factorhavebeenre-vea1edtobeveryuscfulrotlcscribethepropagationlawandthebeamqualityofastaticlightbeam[l~Jj.Rccent1y,1ncji:1sctal.generalizedtheintensitymomentsmethodfortheSCLQ(speetral1y`"el1-centcrcdandlocallyquasi-monochromatic)pulsedlightboms[5j.Itisapparentthatthosercsu]tsubtainedinreferenceL5]areon1yvalidfortheso-calledquasi-monochromaticlightbeamsandarenotvalidforgeneralpolychromaticpulsedlightbeams,esPeciallyaredono…     

Propagation of Light

The speed of light from a uniformly translating source can be deduced, rather than postulated. The deduction, based on the relativity of the Doppler effect, shows that the propagation of light is independent of its source motion (absolute propagation) only if the source is at relative rest. For a relatively translating source, the speed of light in etherless vacuous space is shown to be relative and does depend on the motion-of its source.     

米氏理论的近似及在粒度测量中的应用

将夫琅禾费衍射理论与几何散射 (包括折射和反射 )相结合 ,给出平行光入射下圆形颗粒在前向大角度范围内的散射光强分布近似算法。由于考虑了衍射、折射和反射相互间的干涉效应和颗粒对光的吸收性 ,对于正常或非正常衍射状态下无因次参量α≥ 40的耗散颗粒 ,在前向 0°～ 60°散射之内 ,该方法对散射光强计算结果与米氏理论结果是吻合的。由于计算速度比米氏理论快 ,有效角度范围比夫琅禾费衍射理论宽 ,因而适合于大颗粒的前向光强计算。将这一计算方法应用到大角度采光时的激光粒度测量实验中 ,收到了良好的效果     

基于蒙特卡罗法研究海水中矿物质的光传输特性

为了研究多次散射效应下偏振光在含矿物质粒子海水中的传输特性,建立了一种基于蒙特卡罗法的矢量辐射传输模型.验证了模型准确性,并利用该模型研究了矿物质粒子复折射率、粒子群平均半径和入射光偏振状态对传输特性的影响.模拟仿真结果表明,不同类型矿物质粒子中,较小复折射率实部的粒子,传输特性对复折射率实部变化的敏感性较大;较大复折射率实部的粒子,传输特性对复折射率实部变化敏感性较小.粒子复折射率的虚部是影响光波传输特性的另一重要因素,粒子的吸收性越大,其传输效果越差.随着海水矿物质粒子群平均半径变大,光波透射率降低,反射率增大.圆偏振光与自然光在含矿物质粒子海水中的传输特性相对接近,在海水中,透射率最高的是垂直偏振光,最差的是圆偏振光;反射率最大的是自然光,最小的是水平偏振光.其中水平偏振光传输特性受入射光入射角影响较大.     

吸收介质中微椭球体颗粒光学参数的研究

本文应用Eikonal近似将微椭球用其等效的球来近似, 结合Mie理论对吸收介质中微椭球体颗粒光学参数进行了数值计算。 结果表明, 椭球位置变化时, 散射和吸收性能发生变化。离心率增大时, 散射和吸收系数都增大, 离心率越大增大的越明显。波长增大时, 在紫光波长为0.4 μm和近红外区波长为1.58 μm处散射系数出现了峰值, 而吸收系数单调增大。相对折射率实部以及虚部变化对光学参数均有影响, 颗粒的吸收性越强, 散射相应地减弱。结果表明这种数值解析方法能有效地计算椭球体颗粒的光学参数。     

Dielectric and Polarization Studies of KNO3 Thin Layers

Ultrapure and homogeneous KNO₃ thin layers are subjected to dielectric and polarization measurements over a wide temperature range. The dielectric results obtained are discussed on the assumption of probable formation and migration of vacancies. The variation of polarization with the applied field was found to be nonlinear and the polarization reversal occurs at a critical value of the applied field of strength 11 kV/cm. This value is in good agreement with the value of the coercive field determined previously by the ferroelectric hysteresis loops.     

Light Irradiation through Small Particles and Its Applications for Surface Nanostructuring in Near Field

We investigate the light scattering through small particles and its applications in nanostructuring, such as nanobumping, nanopatterning and dry laser cleaning. The theoretical calculation based on Mie theory provides an exact solution for sphere cavity resonance and plasmon resonance, which are two mechanisms for dielectric and metallic particles assisted surface nanostructuring in near field. The experimental results indicate that nanobumps on glass surface and subwavelength holes array on silicon surface can be formed without cracks with the self-assembly of 1 μm silica particle mask under laser irradiation. It is also found that the scattering wave by 40 nm gold particles can propagate 200 times away in terms of particle radius as recorded by photoresist under the UV light irradiation. Meanwhile, dry laser cleaning of 40nm gold particle on silicon wafer is demonstrated at plasmonic resonance frequency. The total cleaning efficiency is estimated to be 80%.     

Light Front Fermion Model Propagation

In this work we consider the propagation of two fermion fields interacting with each other by the exchange of intermediate scalar bosons in the light front. We obtain the corrections up to fourth order in the coupling constant using hierarchical equations in order to obtain the bound state equation (Bethe-alpeter equation).     

Longitudinal Wave Propagation in Dielectric Waveguide Array

Based on the established rigorous theory for two-dimensionally periodic (2DP) medium, Longitudinal propagation in Dielectric Waveguide Array (DWA) was analyzed in detail. Firstly, given longitudinal wave vector (k _z), Brillouin dispersion relations between transversal wave vectors were analyzed. Interactions between space harmonics were also studied. Secondly, on condition that transversal wave vector k _x equaled k _y, dispersion relations between longitudinal and transversal wave vectors were analyzed in detail. Because of interactions between space harmonics increasingly getting stronger with k _z or modulation coefficients increasing, stop-bands could be distinctly displayed and thus longitudinal propagation in DWA could be comprehensively analyzed. The applications about longitudinal propagation in DWA were also discussed.     

Remarks on Observed Superluminal Light Propagation

A recent experiment [1] shows evidence for strong superluminal group and energy propagation, albeit not for superluminal signal velocity, in light pulses. A few remarks are in order about its implications on the quantum theory of light.     

Fractal Character of Dynamic Light Scattering of Particles

Dynamic light scattering signals from particles, exhibit fractal characteristics. This feature can be used to determine the particle size. The use of the fractal dimension, as a quantitative method to analyze the properties of dynamic light scattering signals from submicron particles, is presented. The analysis is performed directly on the time‐resolved scattered intensity, and the Box Dimensions of light scattering signals of particles with diameters 100, 200, 500 and 1000 nm. The experimental results show that the fractal dimensions of light scattering signals correlate well with particle size. In the submicron size range, the smaller the particles, the larger their fractal dimensions. Compared with the PCS technique, only several hundreds of samples are required in the fractal method. Therefore, the data processing is easily accomplished. However, this method only provides the mean particle size, but not the particle size distribution.     

Exact and Analytical Methods for Finding Complex Roots of Moving Waveguides with Absorbing Layers

We present here two methods of analysis of the complex moving waveguide. One approach is a numerical technique based on Davidenko's method, the other is a perturbation method. Numerical results by Davidenko's method are compared with these obtained from the perturbation method. It is found that the results of the perturbation method are in a good agreement with the numerical one. A comparative study of the propagation and attenuation characteristics of the stationary and moving waveguides has also been investigated and discussed. These results could be used in designing many optical moving sensors.     

Shack-Hartmann波前传感器用于闪烁和相位起伏效应的同时测量

将每一个子孔径及相应的CCD面元作为一个光强探测系统,可以将Shack-Hartmann波前传感器用于湍流大气闪烁效应的测量.分析了该测量方法的基本原理,并结合其波前探测的功能.在近地面水平1km的湍流大气中,同时进行了闪烁和相位起伏的实验研究.将闪烁测量得到的Cn2与大口径闪烁仪测量的结果进行对比,发现两者的相关系数达0.838,验证了Shack-Hartmann波前传感器用于闪烁效应测量的可靠性.对闪烁和相位起伏效应得到的Cn2的日变化进行了对比.结果表明,两者在变化趋势上具有较好的一致性;采用双对数坐标对两种结果进行相关性分析,发现两者的相关系数达0.798.这表明将Shack-Hartmann波前传感器用于闪烁和相位起伏效应的同时测量是可行的,拓展了该传感器的使用功能.     

On the Acceleration of Energetic Cosmic Particles by Electrostatic Double Layers

The capability of electrostatic double layers of accelerating charged particles to high energies is investigated. Starting from a one-dimensional relativistic double-layer model a two-dimensional relativistic double layer in a current filament is studied. It is found that the filamentary double layer has a maximum potential drop that depends both on the magnitude of the filamentary current and on the composition of the layer. The results are applied to two cosmic double layers?one in a solar electric circuit and another in a galactic circuit. If the layers are composed of protons and electrons, these particles may be accelerated to 1011 eV in the solar layer and to 1014 eV in the galactic layer. It is suggested that the solar double layer may account for the acceleration of solar cosmic rays while the galactic layer may contribute to the generation of cosmic radiation.     

包覆微米碳颗粒的光散射特性

利用分层介质球光散射理论公式,计算分析了包覆水和黄铜介质层对碳微粒的微分散射特性的影响,比较了包覆前后散射的极化特性。在计算中为保持收敛性,对Bessel函数采用了递推求解,并对求和项数进行了限定。结果表明,在包覆前后,单粒子的微分散射截面发生了变化,而包覆层的影响与其厚度和光在其中的趋肤深度有关;厚度小于趋肤深度的包覆层对粒子的前后向散射的极化特性没有影响,而在其它方向上却影响较大。     

Binding of Resonant Dielectric Particles to Metal Surfaces Using Plasmons

Forces between dielectric particles induced by optical fields can bind them into new systems, varying from optical molecules to large aggregates. Here it is shown that surface plasmons can bind resonant dielectric particles to the waveguiding surfaces resulting in stable levitation of the particles by the optical forces alone. At the same time, the particles can be propelled efficiently along the surface. The predictions follow from solving the 3D electromagnetic problem of plasmon scattering on a dielectric microsphere near the metal surface. To tackle the problem, an accurate and fast hybrid approach is developed: the fields are expanded into 2D angular components which are calculated using finite-difference time-domain simulations. The rigorous numerical results are also explained qualitatively using an analytically solvable model in which a resonant magnetic dipole illuminated by a plasmon interacts with the surface. The particle binding to surfaces is a remarkable outcome of the strong optical interaction at nanoscale and it may offer new configurations for particle manipulations by guided waves, especially in chip-scale structures.