Interference theory of metamaterial perfect absorbers

摘要

The impedance matching in metamaterial perfect absorbers has been believed toinvolve and rely on magnetic resonant response, with a direct evidence from theanti-parallel directions of surface currents in the metal structures. Here wepresent a different theoretical interpretation based on interferences, whichshows that the two layers of metal structure in metamaterial absorbers arelinked only by multiple reflections with negligible near-field interactions ormagnetic resonances. This is further supported by the out-of-phase surfacecurrents derived at the interfaces of resonator array and ground plane throughmultiple reflections and superpositions. The theory developed here explains allfeatures observed in narrowband metamaterial absorbers and therefore provides aprofound understanding of the underlying physics.