Optically transparent anisotropic holographic impedance metasurface for launching orbital angular momentum vortex wave

Abstract

Abstract The visualization of electronic products is essential for the digitization and visualization of human-computer exchange in the future smart world. However, due to its large non-translucent aperture, the conventional hologram metasurface urgently needs transparency for wide scene usage. In this paper, an optically transparent holographic impedance metasurface with a low profile is investigated for generating orbital angular momentum (OAM) vortex waves in the radio-frequency domain for the first time. Indium tin oxide is applied to perform the metal functionality, which is featured by high optical transparency, and polymethyl methacrylate is proposed as the substrate material in the meta-atom design. By virtue of classic optical metasurface theory and leaky-wave principle, holographic impedance mapping is achieved, so the surface wave generated by the monopole port is effectively converted into a radiating vortex wave at 15 GHz. The prototype has been manufactured and fabricated, and the experiment results exhibit good agreements with theory and simulation analyses, showing a good prospect for OAM vortex wave launch in visualized applications.