Observation of flat band for terahertz spoof plasmons in a metallic kagomé lattice

Abstract

We study the dispersion relation of a metamaterial composed of metallic disks and bars arranged to have kagomé symmetry and find that a plasmonic flat band is formed by the topological nature of the kagomé lattice. To confirm the flat-band formation, we fabricate the metamaterial and make transmission measurements in the terahertz regime. Two bands formed by transmission minima that depend on the polarization of the incident terahertz beams are observed. One of the bands corresponds to the flat band, as confirmed by the fact that the resonant frequency is almost independent of the incident angle.

Non-Drude like behaviour of metals in the terahertz spectral range

“…Since then, many investigators have begun referring to SPPs at THz frequencies as spoof surface plasmons [25][26][27][28][29][30][31][32][33][34][35], even though the terminology is only valid for perfect conductors and not real metals. Nevertheless, the analysis by Pendry et al does give important insight into the effective dielectric properties of metals in the THz spectral range [23,24].…”

Bosonic Condensation and Disorder-Induced Localization in a Flat Band

“…Artificial lattices, recently implemented in a number of physical systems, allow simulating this flat band physics in a controllable manner. Pioneering works in photonic systems [13][14][15][16][17][18][19] and cold atom gases [20][21][22] highlighted the key role played by geometric frustration [15] and evidenced characteristic features such as the absence of wavepacket diffraction in a flat band [17][18][19]. But despite many predictions [23][24][25][26] the specific role played by interactions or disorder has not been experimentally addressed in these artificial lattices so far.…”

Circuit model for hybridization modes in metamaterials and its analogy to the quantum tight‐binding model

“…Our theoretical frameworks can hence be used as a new dispersion design method for metamaterials. We have applied our theory and have experimentally realized a flat band for a metamaterial in the terahertz region 38.…”