Papari Gian Paolo, Koral Can, Andreone Antonello
Department of Physics, University of Naples "Federico II", and CNR-SPIN, I-80125, Naples, Italy.
INFN Naples Unit, via Cinthia, I-80126, Naples, Italy.
Sci Rep. 2019 Jan 30;9(1):924. doi: 10.1038/s41598-018-36648-x.
The transmission response of metallo-dielectric grid metasurfaces is experimentally investigated through Terahertz Time Domain Spectroscopy and the corresponding effective dielectric function is retrieved. Using a lumped element model we can determine the dependence of the effective plasma frequency (the transition frequency) on the metasurface filling factor F. The change of the transition frequency vs. F spans over one order of magnitude and sets the threshold between the metamaterial (homogeneous) and the photonic crystal (diffraction-like) regime, ruling the onset of two different Surface Plasmon Polaritons, spoof and high order. Field symmetry and spatial extension of such excitations are investigated for the possible applications of THz grid metasurfaces in bio- and chemical sensing and sub-wavelength imaging.
通过太赫兹时域光谱对金属-电介质光栅超表面的传输响应进行了实验研究，并检索了相应的有效介电函数。使用集总元件模型，我们可以确定有效等离子体频率（跃迁频率）对超表面填充因子F的依赖性。跃迁频率随F的变化跨越一个数量级，并设定了超材料（均匀）和光子晶体（类衍射） regime之间的阈值，决定了两种不同表面等离激元（仿表面等离激元和高阶表面等离激元）的出现。针对太赫兹光栅超表面在生物和化学传感以及亚波长成像中的可能应用，研究了此类激发的场对称性和空间扩展。
