Frequency-Selective Holographic Imaging Enabled by VO₂-Assisted Reconfigurable THz Metasurfaces

In the terahertz (THz) frequency range, holographic metasurfaces have demonstrated high efficiency and resolution in manipulating electromagnetic waves, allowing for superior imaging solutions. Particularly, reconfigurable holography based on vanadium dioxide $\left(\mathrm{VO}_{2}\right)$ leverages the insulator-to-metal phase transition of VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> to achieve active control over electromagnetic responses. However, existing holographic imaging technologies generally operate in a single frequency band, as VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> primarily functions by adjusting structural parameters. Here, we propose a metasurface design where the VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> elements integrated with the main resonant structure act as a switch, these elements dynamically alter the position of the resonant structure and change the configuration of equivalent unit cell. Consequently, we produce high-efficiency holographic projection of the letters “X” and “ Y “ at 0.5 THz and 0.95 THz, respectively. This work highlights the potential of VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>-assisted metasurfaces for advanced THz devices with versatile functionalities.