亚波长金属槽阵列表面电磁场增强

Surface Electromagnetic Field Enhancement of Sub-Wavelength Metallic Groove Array

针对表面增强拉曼散射的应用,采用严格耦合波分析方法研究了亚波长金属槽阵列的表面电磁场增强效应。模拟阵列周期和槽深对阵列槽口处电磁场增强的影响,明确了结构内部共振效应对电磁场增强的贡献,分析了亚波长金属槽阵列拉曼散射的平均增强效果及阵列外空间中电磁场增强的有效作用范围。研究表明,在槽内共振效应的影响下,亚波长金属槽阵列在一个周期内的拉曼散射增强因子可达106数量级,并在垂直距离阵列表面1/5波长的范围内可得到明显的电磁场增强,超出该范围增强因子将迅速衰减到1的数量级。数值结果表明阵列表面电磁场增强几乎不受贵金属类型的影响。

The surface electromagnetic field enhancement in a sub-wavelength metallic groove array is studied with rigorous coupled wave analysis for surface enhanced Raman scattering. The effects of groove depth and array period on electromagnetic field enhancement at the rabbet of a groove array are simulated. The contribution of resonance effect in structure to electromagnetic field enhancement is achieved. The average enhanced effect of Raman scattering of sub-wavelength metallic groove array and the effective range of electromagnetic field enhancement out of the array are investigated. The results show that with the contribution of resonance in grooves, the Raman scattering enhancement factor of sub-wavelength metallic groove array in one period can reach 106 orders of magnitude. Obvious electromagnetic field enhancement can be obtained at vertical distance to the array surface within 1/5 wavelength, out of which enhancement factor declines rapidly to unitary magnitude. The numerical results show that the surface electromagnetic field enhancement of the sub-wavelength metallic groove array depends weakly on the type of noble metal.