An Application of Metamaterials: Perfect Absorbers

Abstract

We studied structures that describe the perfect-absorber effect by using different mechanisms. Firstly, we investigated the dependences of the reflectance and the absorbance of a metamaterial, as structure proposed by Landy et al. [Phys. Rev. Lett. 100, 207402 (2008)] on gap ‘g’ of the structure at GHz frequencies. The value of the gap was obtained, which gives the maximum absorbance and the minimum reflectance. In addition, the change of geometry of the electric ring resonance as an I-shape made the reflectance disappear at the resonance frequency. A narrow-band peak of the perfect-absorber effect, which was enhanced to be greater than 99.5% at 13.5 GHz, was observed by using a multilayer model for the simplified absorber structure. Secondly, we investigated an absorber structure that includes two metal layers, periodic cut-wire bars at the front and a copper plane at the back, separated by a dielectric layer. The results showed that the absorbance and the resonance frequency of this structure strongly depended on the thickness and the length of the cut-wire bar, respectively. Base on these, we successfully designed a broad-band absorber structure by arranging cut-wire bars with different lengths appropriately in a “meta-atom”.