Enhancing optical transparency of photonic crystals for high-performance electromagnetic interference shielding

In recent years, electromagnetic interference has caused serious threats to both electronic systems and human health. Transparent electromagnetic shielding technology has become a crucial research area for achieving shielding while ensuring optical transparency. This study investigated one-dimensional metal/dielectric photonic crystals on microwave shielding and light transmission. We first found that shielding capability depends primarily on total metal thickness in photonic crystals, rather than its distribution. Particularly, by subdividing the metal into multiple periods with a constant thickness, substantial enhancement in visible transmittance can be achieved while preserving equivalent shielding performance. Accordingly, a high-quality ultra-thin doped silver (8 nm) was employed to construct photonic crystals verifying the assumption. Experiments show that, at a silver film thickness of 24 nm, subdividing into three periods relatively increases the average transmittance by 70.1% (theoretically more than 100%) over the single-layer metal film. Meanwhile, the shielding effectiveness remains consistent for all configurations, with each measurement exceeding -32 dB. In addition, we have established the multi-beam interference-based model to analyze the transmission of microwaves and visible light in photonic crystals. The results are expected to guide refining the optical properties of metal shielding films and exploring the limits of light transmission achievable in experiments for photonic crystals.