Asymmetric transmission (AT) is useful for polarization manipulation. We report narrowband AT that utilizes a triple-layered symmetric trimeric metasurface with near-field coupling of the dark mode of the Fano resonance. The coupling strength of the dark mode was tuned by using a mid-layer to break the dim AT between two slit layers. The peak transmission of linearly polarized waves and percentage bandwidth reached 0.7719 and 1.26% (numerical simulations) and 0.49 and 1.9% (experiments), respectively. Coupled-mode theory and field patterns are utilized to explain the underlying physical mechanisms of the mid-layer assisted field coupling. These results are useful for Fano-resonance-based devices.

中文翻译：

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对称三聚体超表面上基于Fano共振暗模式的窄带非对称传输

非对称传输（AT）可用于极化操作。我们报告了窄带AT，它利用三层对称三聚体超颖表面与Fano共振暗模式的近场耦合。暗模式的耦合强度通过使用中间层来打破两个狭缝层之间的昏暗AT来进行调整。线性极化波的峰值透射率和带宽百分比分别达到0.7719和1.26％（数值模拟）以及0.49和1.9％（实验）。耦合模式理论和场模式用于解释中层辅助场耦合的潜在物理机制。这些结果对于基于Fano共振的设备很有用。