Broadband Plasmon‐Induced Transparency to a Electromagnetically Induced Absorption Conversion Metastructure Based on Germanium

Abstract A Germanium (Ge) metastructure with switching features from broadband plasmon‐induced transparency (PIT) and electromagnetically induced absorption (EIA) is presented, which forms a broadband PIT through the near‐field coupling between the localized plasmon resonance and the Mie resonance employing four gold cut wires as bright plasmon resonators and four C‐shaped dielectric rings as dark plasmon resonators. A wide transparent window above 0.9 is achieved covering from 0.622 to 0.823 THz with a relative bandwidth of 27.8%. In addition, through phase modulation, a magnetic dipole is generated by the constructive interference of the near‐field coupling of the three resonators to realize the PIT to EIA conversion. In addition, a grid‐like metastructure is introduced to realize the PIT to EIA conversion by phase modulation. To enhance the EIA bandwidth, another layer of C‐shaped reflection plate resonator is introduced to increase the dark mode loss, and a layer of frequency selective surface composed of cross‐shaped resonators is also used. Thus under the dual effect, a wide absorption window above 0.75 is achieved covering from 0.647 to 0.756 THz with a relative bandwidth of 15.5%.