Coupling Between Metamolecular Modes and Lattice Diffraction Modes of Metamaterials in Terahertz Region

Abstract

The coupling between plasmonic modes and lattice diffraction modes of circular split-ring resonators in terahertz (THz) region has been analyzed by changing the lattice constants. We discovered a blue shift of the individual eigenmode in short lattice constants, which is due to the longitudinal coupling of two adjacent eigenmodes from neighboring unit cells. We found an anti-crossing effect in long lattice constants for both TM and TE incidence as the lattice diffraction modes is fused with the plasmonic modes to form hybrid modes. Moreover, these hybrid modes are more sensitive to the refractive index change than the pure modes, which shows the promise to increase the sensitivity of metamaterials by coupling.