材料色散对渐变结构一维光子晶体带隙的影响

运用传输矩阵方法及对色散材料采用洛伦兹振子模型,研究了由色散材料构成的介质层厚度为渐变结构的一维光子晶体的带隙特性,并与不考虑材料色散时的光子带隙进行了比较.计算结果表明,考虑色散后的光子带隙既可能变窄也可能增宽,即可能发生红移也可能发生蓝移.光了带隙的改变与色散材料的色散强度和谐振频率及色散前后两介质材料折射率相关.此外,介质材料折射率的变化形式对光子带隙也存在一定的影响.这些为相关光子器件的设计提供了参考.     

CdS纳米晶颗粒薄膜的制备及其光学特性研究

采用化学浴沉积法,以CdCl2·H2O、CS(NH2)2、NH4Cl、NH3·H2O和去离子水作为反应前驱物,在不同的氨水浓度下制备CdS纳米晶颗粒薄膜.通过扫描电镜、X射线衍射、X射线能量色散谱、紫外-可见光透射光谱、椭圆偏振光谱等方法,研究了反应前驱物中氨水浓度对CdS纳米晶颗粒薄膜的表面形貌、晶体结构、S/Cd原子比、光透过率、光学带隙、折射率、消光系数和光学吸收边等物理性能的影响.结果表明:反应前驱物中氨水浓度在0.4～1.0mol/L范围内,可以在衬底上形成均匀致密的CdS纳米晶颗粒薄膜.随着氨水浓度的增加,CdS纳米晶的平均晶粒尺寸逐渐减少,S/Cd原子比逐渐增加,由富Cd型转变为富S型,禁带宽度逐渐增加.在500～1000 nm波段内,折射率的平均值为1.75;消光系数k小于0.07.     

准周期结构一维光子晶体的多重分形特性

利用传输矩阵理论分析了Fibonacci准周期结构的光子晶体的带隙特性,并讨论了当介质层中含有负折射率介质时光子带隙的特性,分析了该准周期结构频谱的多重分形.研究结果表明,Fibonacci准周期结构的分层介质的光子带隙（PBG）特性,不论其为普通介质还是含负折射率介质,其透射谱具有相似性,且随阶数的增大其不均匀性增加.对广义Fibonacci准周期结构——GF（1,n）和GF（m,1）,其透射谱的不均匀性随n和m的增加而增大.     

聚合结晶化胶体阵列结构的压敏光响应性质

制备了由单分散聚苯乙烯微球构成的结晶化胶体阵列结构, 并制备了结晶化胶体阵列聚丙烯酰胺水凝胶薄膜. 通过微区反射光谱研究了其光子带隙位置随外加压力的变化规律. 实验结果表明, 该薄膜在垂直表面方向存在光子带隙, 并在一定载荷范围内带隙波长随外加压力呈可逆线性变化.     

INFLUENCES OF ANISOTROPY ON BAND GAPS OF 2D PHONONIC CRYSTAL

Band gaps of 2D phononic crystal with orthotropic cylindrical fillers embedded in the isotropic host are studied in this paper. Two kinds of periodic structures, namely, the square lattice and the triangle lattice, are considered. For anisotropic phononic crystal, band gaps not only depend on the periodic lattice but also the angle between the symmetry axis of orthotropic material and that of the periodic structure. Rotating these cylindrical fillers makes the angle changing continuously; as a result, pass bands and forbidden bands of the phononic crystal are changed. The plane wave expansion method is used to reduce the band gap problem to an eigenvalue problem. The numerical example is given for YBCO/Epoxy composites. The location and the width of band gaps are estimated for different rotating angles. The influence of anisotropy on band gaps is discussed based on numerical results.     

固-液结构圆柱声子晶体中弹性波的模式和带隙

利用一维固-液结构圆柱声子晶体中弹性波横向受限的条件,推导弹性波在一维固-液结构圆柱声子晶体中各个模式满足的关系式,研究各个模式弹性波的特征.并用色散函数计算各模式弹性波的带隙随模式量子数和圆柱半径的变化规律.得出一维固-液结构圆柱声子晶体的带隙由模式量子数和圆柱半径确定.     

（2＋2）-Dimensional Discrete Soliton Equations and Integrable Coupling System

In this paper, we extend a （2＋2）-dimensional continuous zero curvature equation to （2＋2）-dimensional discrete zero curvature equation, then a new （2＋2）-dimensional cubic Volterra lattice hierarchy is obtained. Fhrthermore, the integrable coupling systems of the （2＋2）-dimensional cubic Volterra lattice hierarchy and the generalized Toda lattice soliton equations are presented by using a Lie algebraic system sl（4）.     

Gray Envelope Solitons in Quantum Electron Plasmas

By using the traditional perturbation method, we obtain the nonlinear Sehrodinger equation for one-dimensional Schrodinger-Poisson system. Some of its solutions can explain previous results.     

Dark soliton in one-dimensional Bose–Einstein condensate under a periodic perturbation of trap

The perturbation of a confining trap leads to the collective oscillation of a Bose--Einstein condensate, thereby the propagation of a dark soliton in the condensate is affected. In this study, periodic perturbation is employed to match the soliton oscillation. We find that the soliton dynamics depends sensitively on the coupling between the moving direction of the trap and that of the soliton. The soliton energy/depth evolves periodically, and a relevant shift in the soliton trajectory occurs as compared with the unperturbed case. Overall, the soliton oscillation frequency changes little even if the perturbation amplitude and frequency vary.     

The Hirota bilinear method for the coupled Burgers equation and the high-order Boussinesq–Burgers equation

This paper studies the coupled Burgers equation and the high-order Boussinesq–Burgers equation. The Hirota bilinear method is applied to show that the two equations are completely integrable. Multiple-kink (soliton) solutions and multiple-singular-kink (soliton) solutions are derived for the two equations.