Highly efficient, polarization insensitive terahertz metamaterial perfect absorber and imaging

摘要

In recent years a great amount of research has been focused on metamaterials, initially for fabrication of left-handed materials for use in devices such as superlenses or electromagnetic cloaking. Such devices have been developed and demonstrated in regimes from the radio frequency all the way to infrared and near optical frequencies. More recently, it has been shown that by careful adjustment of ε̂ andμ̂, near perfect absorbers can be realized High absorption occurs when transmission and reflection are simultaneously minimized. With some clever engineering of the electric and magnetic responses, the electric energy as well as the magnetic energy can be absorbed by a structure. By quick examination of the reflection coefficient relation, equation it can be seen that by adjusting ε̂ and μ̂ such that the effective impedance of the metamaterial is matched to that of free space (Zeff(ω0)= Z0(ω0)), the reflection at ω0 can be minimized.