Perfect Absorption of Light by Coherently Induced Plasmon Hybridization in Ultrathin Metamaterial Film

We demonstrated numerically that light can be totally absorbed by an ultrathin metamaterial film through coherently induced plasmon hybridization. Two fundamental modes, namely symmetrical and antisymmetrical modes, are observed in the metal-insulator-metal structure and attributed to the electric and magnetic resonance, respectively. Each kind of resonance is related to a distinct absorption peak for the corresponding coherent inputs. In particular, it is found that the antisymmetrical absorption is almost omnidirectional and suitable for divergent beams with arbitrary polarization and angle of incidence. To interpret the interaction of magnetic and electric fields with the structure, effective material parameters of the metamaterial are also retrieved, showing good agreement with the intuitive discussion. Furthermore, the general condition of coherent perfect absorption in a metamaterial thin film is given, which could be helpful for the design and understanding of such absorbers.