3D Graphene-like Microstructures for Multi-Frequency Wide-Angle Terahertz Absorption

Three-dimensional (3D) graphene-like microstructures have great potential for terahertz (THz) absorbers, owing to their high electrical conductivity, strong dielectric loss, and unique microstructure. Photosensitive polyimide (PSPI) organic films were commonly used to construct high aspect ratio micrometer structure, and its characteristic size is close to the terahertz wavelength, which is suitable for the development of terahertz absorption devices. In this work, optical lithography and electron beam lithography were combined to induce graphitized carbon films on the surface of PSPI array structure, forming the wafer-level graphene-like/Si/Au sandwich absorber. The test results show that the absorption peaks are located at 0.29 THz, 0.49 THz, 0.70 THz, 0.91 THz, 1.12 THz, 1.32 THz, 1.53 THz, and the absorptions are over 90%. The maximum absorption intensity is close to 99%. Meanwhile, the absorber exhibited outstanding structure insensitivity and wide-angle absorption characteristics across varying structural parameters, size ratios, and incident angles (0–60°). In addition, we further analyzed the absorption properties of the device by varying the thickness of the dielectric layer (50–200 μm), aiming to determine the correlation between the resonant frequency of the absorber and the thickness of the dielectric layer. These results may provide an effective concept and fabrication technique to stimulate many potential applications in emerging terahertz technologies, such as sensing, imaging, and wireless communications.