We realized and experimentally tested a conceptually new kind of electrically thin absorbers of electromagnetic waves. The idea is to utilize a single layer of precisely designed meta-atoms. This allows one to design an absorber with unprecedentedly
small thickness. The absorber implies absence of a ground plane. High efficiency of the realized structure in the S band is demonstrated. The conceptual idea of the proposed absorber can find many applications especially at optical frequencies.
We introduce the concept of non-uniform metamirrors (full-reflection metasurfaces) providing full control of reflected wave fronts independently from the two sides of the mirror. Metamirror is a single planar array of electrically small bianisotropic
inclusions. The electric and magnetic responses of the inclusions enable creating controlled gradient of phase discontinuities over the surface. Furthermore, presence of electromagnetic coupling in the inclusions allows independent control of reflection phase from the opposite sides of the mirror. Based on the proposed concept, we design and simulate metamirrors for highly efficient light bending and near-diffraction-limit focusing with a sub-wavelength focal distance.
In this paper we introduce the concept of metasurfaces which are fully transparent when looking from one of the two sides of the sheet and have controllable functionalities for waves hitting the opposite side (one-way transparent sheets). We address
the question on what functionalities are allowed, considering limitations due to reciprocity and passivity. In particular, we have found that it is possible to realize one-way transparent sheets which have the properties of a twist-polarizer in reflection or transmission when illuminated from the other side. Also one-way transparent sheets with controllable co-polarized reflection and transmission from the opposite side are feasible. We show that particular non-reciprocal magneto-electric coupling inside the sheet is necessary to realize lossless non-active transparent sheets. Furthermore, we derive the required polarizabilities of constituent dipole particles such that the layers composed of them form one-way transparent sheets. We conclude with design and simulations of an example of a nonreciprocal one-way transparent sheet functioning as an isolating twist-polarizer.
