Terahertz perfect absorber with narrowband and broadband absorption based on double cross-shaped and strip-shaped metal patches

This paper proposes a terahertz absorber that combines double cross- and strip-shaped metal patches to achieve narrowband and broadband absorption. The device has a three-layer structure composed of metal–dielectric–metal layers. The top layer features double cross- and strip-shaped metal patches, the middle layer contains a dielectric medium, and the bottom layer is a copper plate. The absorber exhibited three narrowband absorption peaks at 1.211, 1.904, and 3.087 THz, as well as a broadband absorption peak at a frequency of 4–6 THz. The formation mechanisms were elucidated based on the electric field and current distributions at resonant frequencies. An equivalent circuit model was used to calculate the resonant frequencies of various absorption peaks, thereby elucidating the resonance mechanism of the proposed terahertz absorber. Further investigations were conducted to analyze the effects of different structural parameters on the absorber characteristics, and the fabrication process for the absorber is described. The proposed terahertz absorber, which combines narrowband and broadband absorption capabilities, is helpful for applications in terahertz imaging and wireless communication technologies.