Dual-spectral plasmon electromagnetically induced transparency in planar metamaterials based on bright–dark coupling

The optical properties of a planar metamaterials, composed of asymmetric two gold wire pairs located at the two sides of the gold bar, have been investigated theoretically in this paper. The calculated results show that this structure can exhibit dual-spectral plasmonic electromagnetically-induced transparency analogous to the quantum optical phenomenon. The electric field distributions demonstrate that the double transparency windows originate from dual bright–dark coupling modes. Moreover, in accompany with the double tunable transparency windows modulated by the symmetry-reduced displacement, two large group indexes for multi-band slow light applications are also found.