Enhancement of absorption bistability by planar metamaterial

We report on the peculiarities of the absorption bistability which appears in a planar metamaterial composed of a 4-fold periodic array of two concentric metal rings placed on a substrate of saturate absorbing material. Such structure bears the Fano-shape resonance of a trapped-mode excitation which is a result of the antiphase current oscillations in the elements of a periodic cell. It is demonstrated that the switching can be achieved between essentially different levels of transmission nearly the frequency of this resonance excitation.