Design and characterization of metamaterial building blocks using electric current multipoles

We have developed an electrodynamic multipole theory that can be used to characterize the interaction of light with arrays of arbitrary nanoparticles forming a metamaterial. In this theory, every nanoscatterer is substituted with an equivalent point particle in which the incident light excites current multipole moments. The electromagnetic fields scattered by the designed nanoparticles inside the metamaterial are exactly the same as those created by the introduced point multipoles. Thus, we are in a position to assign polarizability tensors that completely characterize the nanoparticles. Tuning the polarizabilities of the higher-order multipoles is essential in order to obtain metamaterials with extraordinary properties.