Metamaterial absorber based on circular rings at infrared frequencies

In this paper, we propose three kinds of metamaterial absorbers at infrared frequencies with simple constitutions. Metamaterial absorber at infrared frequencies can be obtained by reducing the dimensions of the structure to nanoscale with a chemical double-template technique. We first propose a circular ring model. The strongest resonance appears around the frequency of 101.1THz with magnitude of 99.9%. Later, an additional center bar is introduced in the circular ring. The center bar makes the resonance frequency move to higher frequency. The last one is circular ring with center capacitor. The frequency drifts to lower range without decreasing of absorption which can be applied in the design of tunable absorber. As an interdisciplinary subject of physics and chemistry, metamaterial absorbers at infrared frequencies have great prospect in the application of military and other energy detectors.