Metasurface based on phase change materials for electrically reconfigurable THz beam steering in copolarized transmission mode

Metasurfaces are an attractive technology to develop electronically-controlled beam steering devices of THz waves. However, the dynamic steering of co-polarized transmitted waves at a fixed frequency has not been demonstrated yet using this scheme. The performance of this configuration is usually limited by the low phase shifts achievable from thin-film reconfigurable meta-atoms, necessitating the exploration of novel methods. Here, we propose an alternative approach to address this challenge by designing a tunable metasurface utilizing a phase modulation range of only 116. Our design employs a meta-atom array incorporating VO patches within C-shaped split ring resonators (CSRRs). The metal-to-insulator transition of VO enables a continuously tunable phase shift with a reduced amplitude modulation, resulting in a dynamic control over the direction of co-polarized transmitted beams at 0.75 THz in the angular range spanning from -56 to +56. Furthermore, we enhance the device performance by co-optimizing the distribution of phase and amplitude of the gradient profile, leading to an increase in transmission efficiency. This approach can be extended to other regions of the electromagnetic spectrum, accessing applications that require tunable beam steering operation such as imaging, LIDAR, and 6G telecommunications that cannot achieve a 360 phase modulation range.