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, only very few of them meet the stringent electromagnetic interference (EMI) shielding criteria for optoelectronic systems. Here, 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 cut-off 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 62.2 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 19 dB in average shielding effectiveness has been achieved under the same level of light transmission, and the shielding frequency spectrum has been significantly expanded. The working principle has been explained in depth and factors influencing the performance have been investigated for design optimization.