金属和Kerr非线性介质界面上表面等离子体激元的色散关系

从麦克斯韦方程组出发,结合边界条件,分别得到TM波和TE波在金属和Kerr非线性介质界面上表面等离子体激元的色散关系.由于非线性的存在,TM波的色散关系变得复杂,与光强、非线性系数有关.和线性情况一样,此界面不存在TE波.     

Cr4+:YAG飞秒脉冲激光器光路结构的优化设计

通过理论分析和数值计算,对Cr4+:YAG飞秒脉冲激光器光路结构的优化设计进行了研究.提出了在谐振腔内插入一薄聚焦透镜代替另一折叠镜以降低光路的复杂性.为研究起色散补偿作用的棱镜对对腔的稳定性和像散带来的影响,导出了棱镜对的光传输矩阵.通过编程计算得出了连续运转和锁模运转两种工作方式下的不同参数的谐振腔稳区图,对激光器工作点的选择做出了论述.定义了像散补偿失配因子F,做出了像散补偿区域分布图.指出F<0.05的区域具有良好的像散补偿特性,也是激光器光路结构参数设计必须要考虑的重要方面.论证了改变抽运光聚焦透镜的位置可实现抽运光与腔内振荡光的匹配.     

Controlling optical properties of periodic gold nanoparticle arrays by changing the substrate, topologic shapes of nanoparticles, and polarization direction of incident light

The effects of various parameters including thickness and dielectric constants of substrates,shapes of nanoparticles,and polarization direction of incident light,on the extinction spectra of periodic gold nanoparticle arrays are investigated by the full-vectorial three-dimensional (3D) finite difference time domain (FDTD) method.The calculated results show that the substrate affects the extinction spectra by coupling the fields co-excited by the substrate and gold nanoparticles.Extinction spectra are influenced by the shapes of the nanoparticles,but there are no obvious changes in extinction spectra for similar shapes.The polarization direction of incident light has a great influence on the extinction spectra.The implications of these results are discussed.     

The surface plasmon polariton dispersion relations in a nonlinear-metal-nonlinear dielectric structure of arbitrary nonlinearity

The analytic surface plasmon polaritons(SPPs) dispersion relation is studied in a system consisting of a thin metallic film bounded by two sides media of nonlinear dielectric of arbitrary nonlinearity is studied by applying a generalised first integral approach.We consider both asymmetric and symmetric structures.Especially,in the symmetric system,two possible modes can exist:the odd mode and the even mode.The dispersion relations of the two modes are obtained.Due to the nonlinear dielectric,the magnitude of the electric field at the interface appears and alters the dispersion relations.The changes in SPPs dispersion relations depending on film thicknesses and nonlinearity are studied.     

The dispersion relations for surface plasmon in a nonlinear-metal-nonlinear dielectric structure

In the asymmetric and symmetric nonlinear-metal-nonlinear dielectric structures, this paper studies the analytic dispersion relation for surface plasmon in a system consisting of a thin metallic film covered on two sides media of intensity-dependent refractive indexes by applying a generalised first integral approach. Especially in the symmetric waveguide structure, two possible modes can exist: the odd mode and the even mode. The dispersion relations of the two modes are obtained. Due to the nonlinear dielectric, the squared magnitude of the electric field at the interface appears and alters the dispersion relations. Numerical results are compared to those from a certain approximate treatment.