Liu Dejun, Chen Lin, Wu Xiaohu, Liu Feng
Opt Express. 2020 Jun 8;28(12):18212-18223. doi: 10.1364/OE.393230.
One composite plasmonic slab with a broad bandgap (40%) is experimentally and numerically demonstrated in the terahertz (THz) region. The composite slab consists of double-layer metallic gratings and a dielectric film, which supports two resonant modes. Electric field vectors and charge distributions proved that the low-frequency resonant mode originates from the symmetric plasmonic mode, while the high-frequency resonant mode is induced by the hybrid mode of plasmonic and dielectric modes. Compared with the double-layer metallic grating, the inserted dielectric film significantly enhances the transmission of the transverse magnetic (TM) waves and induces Fano resonances. The near-field coupling between metal gratings and dielectric film can be manipulated by changing the thickness and the refractive index of dielectric films. We further demonstrated that the plasmonic bandgap can be manipulated by tuning the grating width. These results suggest that this composite plasmonic slab is promising in terahertz integrated components development such as a filter, polarizer, or sensor.
在太赫兹（THz）波段，通过实验和数值模拟展示了一种具有宽带隙（40%）的复合等离子体平板。该复合平板由双层金属光栅和介电薄膜组成，支持两种共振模式。电场矢量和电荷分布证明，低频共振模式源于对称等离子体模式，而高频共振模式是由等离子体和介电模式的混合模式诱导产生的。与双层金属光栅相比，插入的介电薄膜显著增强了横向磁（TM）波的透射并诱导了法诺共振。通过改变介电薄膜的厚度和折射率，可以调控金属光栅与介电薄膜之间的近场耦合。我们进一步证明，通过调整光栅宽度可以调控等离子体带隙。这些结果表明，这种复合等离子体平板在太赫兹集成元件（如滤波器、偏振器或传感器）的开发中具有广阔前景。
