Terahertz Dielectric Metasurface for Reconfigurable Multifunctional Holographic Dual-Mode Imaging Controlled by Graphene

Metasurfaces are considered the most promising technologies for holographic imaging applications due to their exceptional optical properties and capabilities. However, the work on terahertz (THz) metasurface holographic imaging is relatively limited. Here, we propose a THz dielectric geometric-propagation phase metasurface that can operate in dual modes (reflection and transmission) and enable reconfigurable multifunctional holographic imaging. The dual-mode operation is realized by controlling the Fermi energy level (E_f) of the graphene integrated into the metasurface unit, and the reconfigurable three-channel holographic imaging in reflection or transmission mode are achieved by switching the feed polarization among left-handed circular polarization (LCP), right-handed circular polarization (RCP), and linear polarization (LP). The metasurface is designed based on the transmission mode, and a physical model for switching to the reflection mode is established. For the first time, to the best of our knowledge, a reflection–transmission dynamic modulation THz holographic imaging metasurface has been developed. The holographic metasurface operates in transmission mode at E_f = 0.1 eV and in reflection mode at E_f = 0.9 eV. Compared with recently published holographic imaging metasurfaces, the proposed metasurface offers the following advantages: high holographic efficiencies (42.5% to 49%), more holographic imaging channels, dynamic modulation dual-mode operations, and reconfigurability. The simulation results match the theory.