General strategy for ultrabroadband and wide-angle absorbers via multidimensional design of functional motifs

Abstract

Developing wide-angle, polarization-independent, and effective electromagnetic absorbers that endow devices with versatile characteristics in solar, terahertz, and microwave regimes is highly desired, yet it is still facing a theoretical challenge. Herein, a general and straightforward strategy is proposed to surmount the impedance mismatching in the ultrabroadband and wide-angle absorber design. A vertical atom sticking on N × N horizontal meta-atoms with conductive film is proposed as the functional motif, exhibiting the strong ohmic dissipation along both vertical and horizontal directions. Assisted by the intelligent optimization strategy, the structure dimension, location, and film distribution are designed to maintain absorbing performance under different incident angles. As a demonstration, an absorber was designed and proved in both simulation and experiment. Significantly, the over 10 dB absorption from 5 to 34 GHz is achieved in the range of 0° to 70° for both TE and TM, and even 3 to 40 GHz from 60° to 70° for the TE wave. Meanwhile, the proposed multidimensional design of functional motifs can be attached with optical transparency function at will. That is to say, our effort provides an effective scheme for expanding matching area and may also be made in optical, infrared, and terahertz regimes.