Coupling effect of bright and dark modes in THz metamaterials

The coupling mechanism of bright and dark modes in metamaterials have got enormous attention after the vivid mimicking of electromagnetically induced transparency(EIT) with plasmonic metamaterials. The research progress based on the coupling effects of bright and dark modes over the past few years was reviewed, including the EIT by planar metamaterials, the EIT effect with stereo metamaterials, electromagnetically induced absorption(EIA) from vertically coupling of bright and dark modes and asymmetric excitation of surface wave. The inner mode-coupling mechanism in each unit cell which consisted of the metamaterial determined the far-field and near-field responses. These different coupling mechanisms had important promising value in the designing of functional devices, like optical switch, slow-light devices, sensitive optical sensor and on-chip optical system.