Optically Transparent Frequency-Tunable Microwave Absorber Based on Patterned Graphene-ITO Structure

In this work, the authors report the design, fabrication, and measurement of an optically transparent microwave absorber with tunable absorption frequency based on a patterned graphene-indium tin oxide (ITO) hybrid structure. This transparent tunable absorber consists of periodically patterned graphene sandwich structure (GSS), patterned ITO layer, polyvinyl chloride (PVC) substrate, and ITO ground plane from top to bottom. The frequency of absorption peak can be dynamically controlled from 13.1 to 10.9 GHz by regulating the bias voltage between the graphene sheets from 0 to 30 V, in which the peak absorption rates remain above 99.7%. An inhomogeneous doping model for graphene patterns is introduced to interpret the usage of relatively large tuning voltage. The engineered absorber also exhibits polarization-insensitive characteristics attributed to the symmetrical design of the hybrid structure. This tunable device with optical transparency achieved by integrating different transparent materials has broad prospects in the application of multispectral and smart stealth technology.