Design and experimental characterization of nonlinear metamaterials

We apply an analytic theory [New J. Phys.12, 093010 (2010)] toward the design of varactor-loaded split-ring resonator metacrystals, having nonlinear electromagnetic properties on demand. The design methodology here is shown to be efficient and is validated by the excellent agreement between the analytically predicted and experimentally measured harmonic generation. The analytic formulas enable a path toward optimization of nonlinear properties, which we demonstrate by varying the spacing of the metamaterial elements to maximize the second-order nonlinear susceptibility of the system.