Research on the Transparent Electromagnetic Shielding Method Based on the Ultrathin Metal-Dielectric Photonic Crystal

We have demonstrated a transparent electromagnetic shielding method that under the condition that the thickness of the dielectric in the photonic crystal is significantly thinner than the skin depth of the electromagnetic wave, the shielding effectiveness (SE) of the ultrathin metal-dielectric photonic crystal (UMDPC) is determined by the total thickness of the metallic film (TMF) but not its distribution . With a fixed total metal film thickness, increasing the number of photonic crystal cycles while reducing the thickness of the metal in each cycle can markedly enhance the average visible transmittance (AVT) without altering the SE . When the TMF values go over 40 nm, the microwave shielding effectiveness of UMDPC can surpass 40 decibels. When a 40-nm metal film is set up as a single layer, the average visible transmittance drops below 10%, making it almost completely opaque. If the thickness of the TMF in each cycle is minimized to the smallest achievable dimensions within the permissible range, this allows for an increase in the number of UMDPC cycles. Consequently, the AVT can achieve 60-70%, representing a significant enhancement compared to the singlecycle structure, while the SE remains relatively consistent. The transparent electromagnetic shielding approach suggested in this thesis can effectively solve the challenges of balancing transmittance and shielding effectiveness in devices used for aerospace and aircraft optical windows.