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

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%.