Shorted Micro-Waveguide Array for High Optical Transparency and Superior Electromagnetic Shielding in Ultra-Wideband Frequency Spectrum

While functional materials with both light transmitting and electromagnetic shielding are highly desirable and have made rapid advancements, only very few of them meet the stringent electromagnetic interference (EMI) shielding criteria for optoelectronic systems. Achieving high optical transparency and superior EMI shielding in a broad frequency spectrum is a remaining challenge in both academic and industrial areas. Herein, a design strategy of shorted micro-waveguides (SMWs) array to decouple the light transmission and EMI shielding is proposed and experimentally demonstrated. The array of SMWs, consisting of cutoff metallic micro-waveguides and shorting indium tin oxide (ITO) continuous conductive film, exhibits high optical transmittance of 90.4% and superior EMI shielding effectiveness of 60.8 dB on average over ultra-wide frequency spectrum (0.2–1.3 GHz & 1.7–18 GHz). Compared to previously reported works, an improvement of 17 dB in average shielding effectiveness is achieved under the same level of light transmission, and the shielding frequency spectrum is significantly expanded. The working principle is explained in depth and factors influencing the performance are investigated for design optimization. These outstanding properties enable the transparent shielding material based on SMWs to excel in future applications of EMI shielding for optoelectronic systems.