Ultra-Wideband Optically Transparent Absorbing Metasurface Based on Multilayer ITO Films.

Traditional microwave-absorbing metasurfaces struggle to integrate optical transparency with ultra-wideband and high-efficiency microwave absorption, severely limiting their deployment in optoelectronics-compatible electromagnetic protection. To address this constraint, we propose a transparent ultra-wideband microwave-absorbing metasurface based on multilayered indium tin oxide (ITO) films. The unit cell is constructed using a multilayered PMMA dielectric configuration, where ITO conductive layers are patterned as a top square patch, middle square rings, and a continuous bottom film. Full-wave parametric optimization, combined with multilayer resonant coupling, effectively extends the absorption bandwidth. We elucidate the underlying broadband absorption mechanism by analyzing electromagnetic field and surface current distributions at typical resonant frequencies. Furthermore, we systematically investigate the impacts of ITO sheet resistance, incident angle, and polarization state on absorption performance. A 6 × 6 array prototype is fabricated and experimentally characterized in a microwave anechoic chamber. The measured results demonstrate that the proposed metasurface achieves an absorptance exceeding 90% across 9.2-40.2 GHz, delivering a fractional bandwidth of 125.5%. The experimental responses are in good agreement with numerical simulations, and the fabricated prototype retains good optical transparency. Benefiting from the synergistic integration of ultra-wideband microwave absorption and superior optical transmissivity, this multilayer stacked metasurface offers a promising strategy for advanced optoelectronics-compatible stealth and transparent electromagnetic shielding applications.