Scattering by a Periodic Array of Subwavelength Slits II: Surface Bound States, Total Transmission, and Field Enhancement in Homogenization Regimes
Scattering by a Periodic Array of Subwavelength Slits II: Surface Bound States, Total Transmission, and Field Enhancement in Homogenization Regimes
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DOI：
10.1137/17m1133786
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发表时间：
2017-06
期刊：
影响因子：
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通讯作者：
Junshan Lin;Hai Zhang
中科院分区：
文献类型：
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作者：
Junshan Lin;Hai Zhang
这是一系列的两篇论文的第二部分，关注的电磁场增强和异常衍射的定量分析的周期性阵列的亚波长狭缝。在这一部分中，我们探讨了均匀化制度中的散射问题，其中周期的大小远小于入射波长。特别是，两个均匀化制度进行了研究，其中图案化的狭缝的大小具有相同的顺序作为第一配置中的周期的大小，并且狭缝的大小远小于第二配置中的周期的大小。通过提出严格的渐近分析，我们表明，表面等离子体效应模仿等离子体金属发生在第一均匀化制度。相应的色散曲线位于光线下方，相应的本征模为表面束缚态。此外，对于入射平面波，我们发现并证明了一种新的现象，总传输发生在某些频率的所有入射角，或在一个特殊的入射角，但所有的频率。对于第二均匀化制度，非共振场增强的影响，它表明，在狭缝中的磁场的快速过渡诱导强电场增强。此外，当狭缝的耦合较弱时，增强变得更强。
This is the second part in a series of two papers that concern with the quantitative analysis of the electromagnetic field enhancement and anomalous diffraction by a periodic array of subwavelength slits. In this part, we explore the scattering problem in the homogenization regimes, where the size of the period is much smaller than the incident wavelength. In particular, two homogenization regimes are investigated, where the size of the pattered slits has the same order as the size of the period in the first configuration, and the size of the slit is much smaller than the size of the period in the second configuration. By presenting rigorous asymptotic analysis, we demonstrate that surface plasmonic effect mimicking that of plasmonic metals occurs in the first homogenization regime. The corresponding dispersion curve lies below the light line and the associated eigenmodes are surface bound sates. In addition, for the incident plane wave, we discover and justify a novel phenomenon of total transmission which occurs either at certain frequencies for all incident angles, or at a special incident angle but for all frequencies. For the second homogenization regime, the non-resonant field enhancement is investigated, and it is shown that the fast transition of the magnetic field in the slit induces strong electric field enhancement. Moreover, the enhancement becomes stronger when the coupling of the slits is weaker.