Highly Visible–NIR Transparent Metamaterial-Window for Broadband Microwave Absorption and Shielding

Abstract

Optically transparent metamaterial absorbers have unexceptionally encountered a great challenge in further improving optical transparency ranging from visible (Vis) to near-infrared (NIR) and environmental applicability, due to the limitations of constituent materials and multilayer structures. To overcome this limitation, a highly Vis-NIR transparent metamaterial-window with outstanding microwave broadband absorption and practical durability is proposed in this paper, which adopts a typical sandwich structure consisting of a cross- and cross-ring-shaped resonator and a reflective backplane, separated by a quartz glass. Experimental results indicate that the proposed metamaterial-window achieves >80% absorptivity, covering a wide frequency range of 6.6–13.8 GHz with a relative bandwidth of 70.59%, while the measured shielding effectiveness is >16.94 dB, at 4.0–16.0 GHz. In addition, the corresponding physical mechanism is revealed by exploiting a classical multiple reflections interference model. More significantly, both the patterned resonator and backplane layers are formed by microscale gold meshes with high Vis-NIR transmittance and environmental resistance, thereby enabling excellent salt spray corrosion resistance and high-temperature stability, as well as an average optical transmittance of ≈87.35% at 400–1 800 nm. These advantages endow the design a promising candidate for addressing anti-electromagnetic interference and electromagnetic shielding both in military and civilian.