Transparent EMI shielding and a thermal insulating optical window based on a randomized metallic mesh and ITO-based...

The rapid integration of electronic systems demands multifunctional optical windows that provide high transparency, effective electromagnetic interference shielding, and thermal insulation simultaneously. Existing transparent EMI shielding approaches typically rely on continuous conductive films, silver nanowires, or metallic meshes. These approaches often exhibit insufficient EMI shielding effectiveness and limited optical transmittance, while thermal management is rarely considered. Achieving effective thermal protection while maximizing optical transmittance remains a persistent challenge, limiting their applicability in advanced electro-optical systems. In this work, we propose and demonstrate a novel structure, to our knowledge, combining a randomized metallic mesh with an indium tin oxide-based coating on a fused silica substrate. This design overcomes the long-standing trade-offs among optical, electromagnetic, and thermal functionalities in transparent shielding windows. To address higher-order diffraction effects in periodic meshes, a randomization optimization strategy was employed to homogenize diffraction intensity and improve imaging quality. By fabricating the metallic mesh and the ITO-based coating on opposite sides of the substrate, we significantly enhanced the EMI shielding effectiveness without compromising the overall optical transmittance. Experimental results show that the fabricated samples achieve a high transmittance exceeding 85% in the 400-700 nm wavelength range and a superior EMI shielding effectiveness of 37-44 dB in the X-band (8.2-12.4 GHz). Furthermore, the ITO-based thermal protection coating provides over 90% reflectance in the 2-14 µm infrared range, enabling significant thermal insulation. The proposed design effectively balances optical, electromagnetic, and thermal responses, offering a robust solution for advanced electro-optical systems in complex environments.