Broadband-absorption mechanism in a water-based metamaterial absorber

Bulky water has been used to construct broadband metamaterial absorbers (MAs). Herein, a broadband MA using sheet of water instead of bulky water is proposed for terahertz domain. The proposed structure has excellent stability to wide incident angles. Most important, the proposed structure surpasses those based on bulky water in terms of absorption performance. The distributions of field and power loss are investigated, which reveal that power loss is mostly contributed by magnetic resonance occurring at the borders of water and PDMS and thus broadband absorption is dependent on the contact area of water and its surrounding dielectric. Therefore, the designed absorber based on sheet of water is superior due to larger contact area. This provides an enlightenment that maximizing contact area between water and its surrounding dielectric such as using sheet of water can enhance absorption performance in the design of water-based MAs, which can facilitate the design. The results of this work may be directive and helpful for designing water-based broadband absorbers. • A metamaterial absorber based on sheet of water is proposed for terahertz domain. • The absorber surpasses those based on bulky water in absorption performance. • Magnetic resonance plays the dominant role in broadband absorption. • Magnetic resonance mainly occurs at the borders of water and PDMS. • The research may provide guidance of design of broadband absorbers based on water.