VO2-enabled transmission-reflection switchable coding terahertz metamaterials.

Coding metamaterials have offered unprecedented degrees of freedom to manipulate electromagnetic waves in time and frequency domains in terms of various coding sequences, however, it is still challenging to realize dynamic coding metamaterials in the terahertz range. Here, we propose VO2-enabled transmission-reflection switchable coding terahertz metamaterials consisting of multilayered gold and VO2 patterns. The insulator-to-metal transition of VO2 leads to switch between the refractive and reflective scattering beams by changing the temperature. The four 2-bit elements are used to construct coding metasurface-based OAM generator with l = 1. Remarkably, the transmission-reflection switching functionality of the coding metasurface can be achieved at different frequencies. In addition, the novel designs in our work can achieve EM waves manipulation and provide a useful method to dynamically switch transmission-reflection response in the THz frequency regime.