二维金属波导阵列的亚波长自聚焦效应

Study of Subwavelength Self-Focus Effect in Two-Dimensional Ag-waveguide Arrays

利用时域有限差分(FDTD)方法对不同入射波长和不同结构参量的Ag波导阵列自聚焦现象进行了数值分析.分析表明:焦点位置与光源到Ag波导阵列的距离s,Ag波导阵列入射面形状以及入射波长有关.随着光源到Ag波导阵列距离s的增大,焦点位置逐渐变远;随着入射面凹陷步长b减小,焦点位置逐渐变远;随着入射面凹陷深度d的增大,焦点位置逐渐变远.入射面的形状可以较大程度影响焦点位置以及焦点处的光强.当Ag波导阵列的结构一定时,自聚焦的焦点位置均与入射波长成线性关系.结果表明,可以通过适当地调节参数得到理想的焦点位置.

Subwavelength self-focus effect in a set of nanoscale Ag-waveguide arrays （Ag-WGAs） is numerically simulated with the finite-difference time-domain （FDTD） method. The result shows that the self-focus behavior can be modulated significantly by tuning the distance between the light source and the input facet of the Ag-WGAs, the surface configuration of Ag-WGAs and the wavelength of the incident wave. The surface configuration of the waveguide arrays has enormous effects on the focal distance and the corresponding intensity of light. It is also found that the focal distance is increased linearly with the incident wavelength. The focal distance can be controlled by the structural parameters.