Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces
Highly confined guiding of terahertz surface plasmon polaritons on structured metal surfaces
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DOI：
10.1038/nphoton.2007.301
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发表时间：
2008-03-01
期刊：
影响因子：
35
通讯作者：
Garcia-Vidal, F. J.
中科院分区：
文献类型：
--
作者：
Williams, C. R.;Andrews, S. R.;Garcia-Vidal, F. J.
超材料是具有亚波长结构(1)的人造材料，能够将磁(2)和电响应(3)转换成自然产生的材料无法到达的光谱区域。在这里，我们报道了对太赫兹电磁表面模的传播和限制的直接测量，该表面模紧密地束缚在平面等离子体超材料上，该材料由装饰有二维亚波长-周期凹坑阵列的金属表面组成。这些模式是表面等离子体激元，其有效等离子体频率完全由表面几何形状控制(4)。模式光谱和对空气的穿透深度显示出强烈的波长尺度的能量限制在电磁带边缘以下的表面；这与在这种光谱制度下在平坦的金属表面上发现的非常弱的限制形成鲜明对比。研究结果与表面等离子体激元在结构理想导体表面传播的解析和数值模型相吻合，表明等离子体超材料可以帮助光学元件小型化或改进化学或生化传感器。
Metamaterials are artificial materials with subwavelength structure(1) that enable the translation of magnetic(2) and electric responses(3) into spectral regions not accessible through naturally occurring materials. Here, we report direct measurements of the propagation and confinement of terahertz electromagnetic surface modes tightly bound to flat plasmonic metamaterials that consist of metal surfaces decorated with two- dimensional arrays of subwavelength- periodicity pits. These modes are surface plasmon polaritons with an effective plasma frequency controlled entirely by the surface geometry(4). The mode spectrum and penetration depth into air demonstrate strong wavelength- scale energy confinement to the surface below the electromagnetic band edge; this is in stark contrast to the very weak confinement found at flat metal surfaces in this spectral regime. The results are in good agreement with analytical and numerical models of surface plasmon polaritons propagating on structured perfect- conductor surfaces, and imply that plasmonic metamaterials could help miniaturize optical components or lead to improved chemical or biochemical sensors.