梯度圆柱颗粒复合介质的有效非线性响应

应用非线性微分有效偶极近似方法,导出了关于非线性梯度圆柱颗粒的等效线性介电常数和三阶非线性极化率的微分式,研究了稀释极限下,圆柱形梯度颗粒无规置入线性介质中组成的复合介质的有效线性介电常数和三阶非线性极化率.作为应用,数值计算了具有幂指数梯度分布的介电常数的颗粒复合介质的有效非线性响应,及梯度金属电介质颗粒复合介质的表面plasmon共振效应.     

梯度颗粒复合介质的光学双稳

重点研究了组分的梯度构形对带壳球形颗粒复合介质的光学双稳特性的影响.其中球形颗粒是由非线性核和介电函数具有梯度分布的线性壳组成.对于壳层介电函数具有幂指数分布的情况,通过求解麦克斯韦方程,得到各区域的势能分布函数,从而求得核内电场的数学表达式.数值研究发现,该复合介质的光学双稳阈值和区域与壳层的厚度及壳层的介电幂指数有关,随着壳层厚度增大或幂指数增大,双稳阈值将变宽.此外,还研究了正入射情况下复合材料体系的反射系数随外电场的变化情况, 发现其关系曲线是一条回线. 关键词： 梯度颗粒 复合介质 光学双稳     

非均匀介质球颗粒的等效介电常量

从求解拉普拉斯方程的边值问题出发,讨论了非均匀介质球颗粒的等效介电常量,给出了多种介质组成的多壳层介质球颗粒的等效介电常量的一般递推公式,推导了壳层的介电常量随半径连续变化的梯度介质球的等效介电常量的微分方程．并以壳层的介电常量为幂函数为例,得到了梯度壳层介质球的等效介电常量．     

具有各向异性的梯度颗粒复合材料的有效介电响应

本文研究了具有梯度壳层椭球颗粒复合体系的有效介电响应，在稀释条件下用准静态近似方法, 推导了颗粒壳层具有任意介电梯度形式的椭球颗粒复合体系的有效介电常数和部分共振条件的一般表达式。并以壳层的介电常数为主轴的幂函数形式为例，得出了通过调节壳层的介电梯度形式、颗粒的结构和形状,可以提高该体系的有效介电常数和实现部分共振的结论。     

非局域颗粒复合介质的相干完美吸收效应

研究了两束相干光以相同的入射角从左、右两侧分别入射到Au-SiO_2复合介质板时,在不同的体系参数下该复合材料体系发生相干完美吸收的情形.运用有效媒质理论推导出了复合介质的有效介电常数以及有效磁导率;在得到有效电磁参数的基础上进一步推导得到平面波入射复合介质板时的反/透射系数.通过比较分析非局域和局域情况下颗粒复合介质的相干完美吸收现象,发现当颗粒尺寸很小时非局域效应的影响会导致复合介质产生相干完美吸收的入射光的频率范围显著变宽.在进一步的解析计算中,通过调节复合介质板的厚度、入射光波长、金属颗粒体积分数等参数得到了不同情况下产生的相干完美吸收现象,并由此分析非局域情形下对于相干完美吸收现象的调控.     

用Bergman方法计算复合介质的电势分布

从第一性原理出发,利用Bergman表示理论,推导出二元复合材料系统中电势表达式,并通过数值计算求出体心四方、体心立方、面心立方等几种周期性结构复合材料中的电势分布- 关键词：     

金属/电介质颗粒复合介质的非线性交流响应

推广T矩阵法来研究二组分颗粒复合介质的非线性交流响应，解析推导出基频、三次及五次谐波频率下的有效线性介电常数及三阶和五阶非线性极化率的解析表达式.当组分颗粒的介电常数为实数时，表达式同以前微扰理论完全一致.进一步数值计算了金属-电介质复合介质的有效非线性交流响应，数值结果表明，体系的三阶、五阶非线性极化率在表面等离子共振频率附近有明显增强，而且，随着体积分数提高，共振峰增强且伴随着共振频率红移现象.还进一步讨论了维度效应对体系非线性交流响应的影响. 关键词： T矩阵方法 复合介质 非线性交流响应     

球形粒子复合介质非线性有效电导交流响应

利用摄动方法，研究了在外加交流电场作用下，含球形杂质的非线性复合介质有效电导的交流响应问题。在一类形如E1sinωt +E3sin3ωt的正弦电场作用下，分别导出了非线性复合介质中杂质粒子及基质所在区域的局部电势。在杂质浓度较低时，进一步得到了复合介质非线性有效电导在基频和三阶谐波下的响应，并讨论了二者之间的关系。     

颗粒复合介质在高温下的光学双稳特性

利用Maxwell-Garnett近似，结合谱表示方法，理论研究了金属/绝缘颗粒复合介质的光学双稳特性随环境温度的依赖关系.数值结果表明，体系的光学双稳区域随环境温度的升高而逐渐变窄，甚至消失.还进一步研究了复合体系的折射系数和消光系数随温度的变化关系. 关键词： 颗粒复合介质 光学双稳     

非线性柱形涂层复合介质有效的直流-交流电响应

利用摄动展开方法, 研究了由圆柱形带涂层杂质随机嵌入基质所形成的非线性复合介质在外加 的带有不同频率和振幅的混合电场E₀ + E₁ sinωt+E₃ sin3ωt作用下有效的直流-交流电响应, 分别推导了复合介质在杂质核、涂层及基质区域的电势分布, 并在低杂质浓度下给出了复合介质有效的非线性响应及它们之间的关系. 关键词： 非线性柱形涂层复合介质 有效的非线性响应 外加交直流电场     

Effective Dielectric Response of Composites with Graded Material

The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E₀. For the cylindrical inclusion with gradient dielectric function, ε_i(r)=b+cr, randomly embedded in a host with dielectric constant ε_m, we have obtained the exact solution of local electric potential of the composite media regions, which obeys a linear constitutive relation D=εE, using hypergeometric function. In dilute limit, we have derived the effective dielectric response of the linear composite media. Furthermore, for larger volume fraction, the formulas of effective dielectric response of the graded composite media are given.     

Effective AC Response of Nonlinear Spherical Coated Composites

Under alternating current electric field, effective response of granular nonlinear composites with spherical coated inclusions is investigated in the dilute limit by using the perturbation approach. For an external sinusoidal applied field with finite frequency ω, the local fields and potentials of composites in general consist of components at all harmonics for cubic nonlinear constitutive relationships. We derive the local potentials of spherical coated composites at harmonics. Moreover, we give the formulae of the nonlinear effective AC susceptibility at the third harmonic frequency.     

Effective Anisotropic Dielectric Properties of Crystal Composites

Transformation fieM method （TFM） is developed to estimate the anisotropic dielectric properties of crystal composites having arbitrary shapes and dielectric properties of crystal inclusions, whose principal dielectric axis are different from those of anisotropic crystal matrix. The complicated boundary-value problem caused by inclusion shapes is circumvented by introducing a transformation electric field into the crystal composites regions, and the effective anisotropic dielectric responses are formulated in terms of the transformation field. Furthermore, the numerical results show that the effective anisotropie dielectric responses of crystal composites periodically vary as a function of the rotating angle between the principal dielectric axes of inclusion and matrix crystal materials. It is found that at larger inclusion volume fraction the inclusion shapes induce profound effect on the effective anisotropic dielectric responses.     

Dielectric responses of graded composites having generalized gradation profiles

Under an external uniform electric field, the dielectric response of graded cylindrical composites having generalized dielectric profile inclusions is investigated. The generalized dielectric profile of graded cylindrical inclusion is expressed in the form, $\varepsilon _i (r)=c(b+ r)^k\e^{\beta r}$ where $r$ is the radial variable of the cylindrical inclusions and $c$, $b$, $k$ and $\beta $ are parameters. The local potential solution of generalized dielectric profile graded composites is derived by means of the power series method and the effective dielectric response is predicted in the dilute limit. Moreover, from the result of generalized profile, the analytical solutions of local potentials and the effective responses of graded composites having three cases of dielectric profiles, i.e., the exponential profile $\varepsilon_\i (r)=c\e^{\beta r}$, the general power law profile $\varepsilon_\i (r)=c(b+r)^k$ and the profile $\varepsilon_\i (r)=cr^k\e^{\beta r}$, are sorted out, respectively. In the dilute limit, our exact results are used to test the validity of differential effective dipole approximation (DEDA) for estimating the effective response of graded cylindrical composites, and it is shown that the DEDA is in excellent agreement with the exact result.     

Measurements of Optical Trapping Efficiency for Micron-Sized Dielectric Particles in Various Surrounding Media

The maximum axial trapping efficiency Q_max has been measured in water, ethanol, butanol and octanol for polystyrene latex spheres having a diameter of 2–15μm. The effects of the diameter of the particle as well as the refractive index and the viscosity of surrounding medium have been investigated. For particles of d≥7 μm, Q_max is almost independent of particle size, while it decreases as the diameters decrease to d≦5 μm. It is also noted that Q_max is affected by the viscosity rather than the refractive index of the surrounding medium.     

Idealization Second Quantization of Composite Particles

A practical method is developed to deal with the second quantization of the many-body system containing the composite particles.In our treatment,the modes associated with composite particles are regarded approximately as independent ones compared with those of unbound particles.The field operators of the composite particles thus arise naturally in the second quantization Hamiltonian.To be emphasized,the second quantization Hamiltonian has the regular structures which correspond clearly to different physical processes.``     

温度对线状金属颗粒复合物电磁参量的影响

线状金属颗粒在复合物中会构成回路,产生较强的磁响应,这种磁响应受温度影响小.基于有效介质理论,探讨线状金属颗粒复合材料电磁响应的基本特征,优化设计适用于高温环境的、性能较好的线状钨颗粒复合微波吸收材料.     

Idealization Second Quantization of Composite Particles

A practical method is developed to deal with the second quantization of the many-body system containing the composite particles.In our treatment,the modes associated with composite particles are regarded approximately as independent ones compared with those of unbound particles.The field operators of the composite particles thus arise naturally in the second quantization Hamiltonian.To be emphasized,the second quantization Hamiltonian has the regular structures which correspond clearly to different physical processes.     

Effective Response of Nonlinear Spherical Coated Composites Under External AC and DC Electric Field

Under the external AC and DC electric field, the effective response of nonlinear spherical coated composites, which obey the constitutive relation of electric displacement and electric field, is investigated in the dilute limit by using the perturbation method. The local potentials in inclusion and host regions are derived at all harmonics. Moreover, the formulae of the effective linear and nonlinear responses are given in the dilute limit.