Tunable Broadband Terahertz Metamaterial Absorber Based on Graphene

This paper puts forward a novel proportional structure for a tunable broadband absorber in the terahertz (THz) frequency band, with graphene as its core material. In the pursuit of an optimal design, we maintain a proportional distance between the top graphene structure and the periodic edges. This design enables excellent absorptance, surpassing 90% in the 2.89–6.43 (3.54) THz frequency range. Notably, at f = 4.25 THz, perfect absorption is achieved. At f = 5.8 THz, the absorptance nears 95%, and at f = 5.47 THz, it is around 91%. The average absorptance within the 2.89–6.43 THz range reaches 94.5%. By calculating the impedance of the absorber, the favorable absorption frequency band is demonstrated. Moreover, analyzing the internal electric field of the absorber reveals a strong electric field coupling effect between different regions. This effect leads to the overlap of absorption peaks, thus forming a broadband response. This characteristic allows for the selection and combination of regions according to application requirements. By adjusting the absorber's parameters, it shows coordinated performance and manufacturing tolerance. Additionally, the absorber exhibits a certain tolerance to the incident angle of electromagnetic waves. These findings highlight the potential of this absorber in applications such as optoelectronic devices, THz detection, and stealth technology.