Mesh-based metasurfaces with high optical transparency

A metasurface technology is proposed, which uses a fine-line-based mesh to form a resonant structure instead of the traditional resonant pattern. Because the filling factor of the fine lines is low, the metasurface has high optical transmittance. Meanwhile, a highly efficient electromagnetic absorption can be achieved through the stacking of the metasurfaces. To demonstrate the effectiveness, we designed an optically transparent microwave absorber with polarization insensitivity and wide-angle incidence characteristics. The absorber is composed of a top mesh metasurface film, a transparent layer, and a bottom mesh film. Next, the sample with an area of 150 × 150 mm² was fabricated using nano-imprinting technology. Through testing, the top metasurface and the bottom film achieved an average optical transmittance of 91.53% and 92.67%, respectively. Furthermore, by adjusting the stacking gap (transparent layer thickness), the absorption rate could be adjusted from 94.15% to 18.4%. Embedding the metasurface films into transparent windows or materials can achieve both efficient electromagnetic absorption and optical transparency.