Water-based metamaterials absorber with broadband absorption in terahertz region

A water-hybrid metamaterial absorber composed of water and a cross-shaped gold resonator in terahertz (THz) range is proposed, which can achieve absorption exceeding 90% from 3.65 to 10.54 THz at normal incidence with a relative bandwidth of 97.1%. By incorporating water with excellent frequency dispersive permittivity into the absorber, the absorption bandwidth of the proposed absorber is effectively expanded, providing an effective method to broaden the absorption band in the THz region. The mechanism of broadband absorption is illustrated by analyzing electric field distribution, and the physical mechanism of high absorption is revealed by using impedance matching theory. In addition, the proposed absorber is also characterized by polarization insensitivity and good thermal stability, and it can maintain a high absorption of more than 90% from 3.92 THz to 10.50 THz with the incident angle below 41°. Therefore, due to its preeminent performance, the absorber can be a potential candidate for energy harvesting, thermal detector, and stealth technology applications. •A water-hybrid ultra-broadband metamaterial absorber in terahertz region was proposed.•The absorption bandwidth of the absorber is effectively expanded by incorporating water into the absorber.•The absorption bandwidth over 90% of the absorber reaches 6.89 THz with a relative bandwidth of 97.1%.