Visible-Infrared Transparent Ultra-Thin Frequency-Tunable Microwave Absorber Based on a Nanometer-Thick Patterned VO2 Film

Designing an ultra-thin microwave absorber that can simultaneouslyrealize tunable absorption and broadband optical transparency remainsa crucial challenge. In this work, we present a visible-infraredtransparent ultra-thin frequency-tunable microwave absorber basedon a nanometer-thick patterned vanadium dioxide (VO2) film.The thermally variable sheet resistance of the nanometer-thick VO2 film enables different percentages of equivalent resistancein the equivalent impedance of the patterned VO2 film,which induces the absorbing mode to transform from pure Fabry-Perot(FP) cavity resonant to FP cavity and LC electrical co-resonant. Themeasured thermally peak absorption frequency modulation range is 15.42-12.99GHz, while the ultra-thin thickness is only 0.071 of the central wavelengthof this range. Moreover, the absorber can achieve high optical transparencyfrom 380 to 6000 nm. Therefore, the proposed absorber has diverseapplications in optics and modern intelligent platforms.