Switchable coding metasurface for flexible manipulation of terahertz wave based on Dirac semimetal

In this study, a switchable coding metasurface was demonstrated in the terahertz (THz) frequency range to realize dynamic beam steering based on a Dirac semimXetal. The relative phase delay of the proposed metamaterials unit cell can be actively controlled by changing the Fermi level (EF) of the Dirac semimetal film (DSF). For the 1-bit coding metasurface, the coding units with '0 ' and '1 ' states can be switched on/off in the frequency range of 1.46-2 THz by changing the EF value of the DSF. The beam numbers and propagation direction of the reflected waves in such 1-bit coding metasurfaces can be engineered at will. Moreover, a dynamically controlled 2-bit coding metasurface was constructed based on DSF microstructures to realize more sophisticated beam manipulation. When EF was set to 0.3 eV, the relative phase delay of the four-unit structure at 1.0 THz was increased from 0 degrees to 360 degrees with an interval of 90 degrees. When EF decreased to 0.02 eV, the relative phase delay of the four-unit structure was reduced accordingly, and the phase coverage decreased to only 30 degrees. Based on the above results, switching between abnormal/specular reflection and on/off vortex generation were realized. The proposed coding metasurfaces are promising for use in THz communication and sensing applications.

Automated summary

This study demonstrates a switchable coding metasurface in the terahertz frequency range for dynamic beam steering. By changing the Fermi level of the Dirac semimetal film, the relative phase delay of the metamaterials unit cell can be actively controlled, allowing for engineering of beam numbers and propagation direction. Furthermore, a 2-bit coding metasurface based on microstructures is constructed to achieve more sophisticated beam manipulation.