Reconfigurable chiral metasurface based on vanadium dioxide: Modulation of phase and intensity for high-quality hologram and near-field imaging

Circular dichroism (CD) has gained significant recognition in the field of artificial materials. However, there is still a need for a flexible approach to modulate CD, which would enable spin-selective multidimensional manipulation of terahertz (THz) waves. In recent years, reconfigurable metasurfaces have emerged as a prominent area of research in the field of micro/nanophotonic. This study proposes a novel reconfigurable chiral metasurface utilizing the phase transition properties of vanadium dioxide (VO2), capable of modulating CD. This metasurface not only realizes the modulation of the Pancharatnam-Berry (PB) phase in two states of VO2 but also enables the modulation of CD at the dual THz band. Based on the principle of the PB phase to control the phase of the meta-atom, the 3-bit coded metasurface arrays were proposed to achieve high-quality THz holographic imaging. Furthermore, the near-field imaging effect is realized by utilizing the differentiation property of the absorption intensity of chiral CD meta-atom. This multifunctional device, with its simple structure, exhibits tremendous potential for applications in THz holographic imaging, THz circular polarized wave detection, and image encryption.