Terahertz Broadband 1-bit PB-phase Metasurfaces via independently controlled flip-chipped HEMT-atoms

High-performance reconfigurable intelligent surfaces have demonstrated significant potential in achieving precise and wide-angle terahertz beam steering. This study introduces a double-layer metasurface independently coded to leverage the Pancharatnam-Berry (PB) phase for 1-bit terahertz beam steering. The metasurface design ensures smooth phase shifts and consistent amplitudes across a broad frequency spectrum, enabled by flip-chipped PB-phase elements. Notably, an upper dual-split square ring resonator enhances the cross-polarization conversion of the HEMT-controlled PB-phase structure and interlayer coupling. Simulation results indicate a phase difference of 180° within the 0.122-0.16 THz band, phase shift errors below 2°, insertion loss less than -6.13 dB, and a scanning range exceeding ±60° in two dimensions. With quasi-ideal coding states and straightforward fabrication, this metasurface holds promise for applications in 6G wireless communications and terahertz radar detection.