Dynamically tunable multi-channel and polarization-independent electromagnetically induced transparency in terahertz metasurfaces

Abstract

Switchable multi-channel electromagnetic induced transparency (EIT) is achieved in designed terahertz metasurfaces. The underlying physics of the EIT effect is analyzed. The influence of structure parameters on the EIT effect is investigated. A metasurface with a symmetrical unit cell is proposed, by which polarization-independent EIT is achieved. In addition, photosensitive silicon is integrated into the metal layer aiming for active modulation. Tunable EIT with adjustable peak frequency and amplitude is obtained. Moreover, the dynamic control is not limited to a single EIT transparency window. We show that the number of EIT transparency windows can be tailored, and switchable multi-channel EIT are successively realized. The results would provide significant guidance in multifunctional active devices, such as modulators and switches in nanophotonics optics.

Quad-band terahertz metamaterial absorber enabled by an asymmetric I-type resonator formed from three metallic strips for sensing application

“…It can be predicted that the absorption performance of the metamaterial absorber, especially the number of the absorption peaks, could be adjustable when the vertical metallic strip C is replaced by a materials having the features of changing from the medium property to metallic property. Photosensitive silicon material is a kind of suitable material, which can realize the transition from medium to metallic through external stimulation of such as pump light intensity [35]- [37]. With the increase of external stimulation intensity, the conductivity of photosensitive silicon can gradually increase, thus realizing the transformation from the dielectric property to metallic property [35]- [37].…”

“…Photosensitive silicon material is a kind of suitable material, which can realize the transition from medium to metallic through external stimulation of such as pump light intensity [35]- [37]. With the increase of external stimulation intensity, the conductivity of photosensitive silicon can gradually increase, thus realizing the transformation from the dielectric property to metallic property [35]- [37]. We here give an adjustable metamaterial absorber using photosensitive silicon instead of the vertical metallic strip in the original asymmetric I-typed resonator.…”

Electromagnetically induced transparency metamaterials: theories, designs and applications

“…In section 3, the construction methods of passive EIT metamaterials in the microwave [78][79][80], terahertz [81,82], and optical frequencies [83][84][85] are reviewed. In section 4, many approaches of dynamically controllable EIT effects are discussed by introducing active materials into metamaterials such as graphenes [86][87][88][89][90], photosensitive materials [91][92][93], microelectromechanical systems (MEMs) [94], and phase change materials [95], etc. Following this, the properties of EIT metamaterial-based for refractive index sensing [96][97][98][99][100][101][102][103][104][105], slowing light [106][107][108][109][110][111][112][113], enhancing absorption [114][115][116][117][118] are also reviewed in section 5.…”

Polarization-independent analog of electromagnetically induced transparency based on longitudinal and transverse mode coupling

“…To obtain polarization-independent EIT-like devices, many complex structures have been designed 8 , 23 – 27 However, these structures, such as other polarization-sensitive EIT-like devices, still use the coupling effect between the transverse resonance modes to obtain the EIT effect. In fact, optical metamaterial devices not only have transverse resonance modes but also can obtain EIT-like effects using longitudinal modes 7 …”