Laser direct writing graphene assembly film for realizing plasmon-induced transparency at terahertz region

Terahertz (THz) metasurfaces, which combine the low energy and high transmission properties of THz wave with the flexible modulation characteristic of electromagnetic derived from metasurfaces, have made tremendous research progress in the field of filtering, security, 6G communications and bio-sensing. However, the practical application of THz metasurfaces is limited by the complex preparation process and the small sample area. Herein, we propose a large-scale flexible metasurface by introducing laser direct writing (LDW) fabrication method which can directly ablate the designed patterns on the wafer through the heat of laser. This proposed flexible metasurface can achieve a typical plasmon-induced transparency (PIT) effect in the reflection spectra at terahertz region by introducing a novel graphene assembly film (GAF) whose conductivity reaches 1.1 × 106 S·m−1 that is close to metals. In addition, the LDW processing method ablates the designed pattern on the GAF by laser heat, which only takes 30 min to complete the large area of 229 mm × 305 mm metasurface owing to fast-scanning speed of the mirrors and large scanning area of the LDW system, and the ablation precision can reach 50 μm. It is foreseen that this processing method using LDW on GAF, with its advantages of rapid fabrication, large area, low cost and flexibility, will provide a new way for the development of THz devices.