Polarization-dependent electromagnetic responses of ultrathin and highly flexible asymmetric terahertz metasurfaces

We report the polarization-dependent electromagnetic response from a series of novel terahertz (THz) metasurfaces where asymmetry is introduced through the displacement of two adjacent metallic arms separated by a distance delta. For all polarization states, the symmetric metasurface exhibits a low quality (Q) factor fundamental dipole mode. By breaking the symmetry, we experimentally observe a secondary dipole-like mode with a Q factor nearly 9 x higher than the fundamental resonance. As ffi increases, the fundamental dipole mode f(1) redshifts and the secondary mode f(2) blueshifts creating a highly transmissive spectral window. Polarization-dependent measurements reveal a full suppression of f(2) for all asymmetries at theta >= 60 degrees. Furthermore, at delta >= 60 mu m, we observe a polarization selective electromagnetic induced transparency (EIT) for the fundamental mode. This work paves the way for applications in filtering, sensing and slow-light devices common to other high Q factor THz metasurfaces with EIT-like response. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement