Electromagnetically induced transparency controlled by auxiliary wave via three-wave mixing

We introduce a metamaterial for realizing true electromagnetically induced transparency (EIT) in analogy to atomic EIT effect. In the metamaterial, two resonant modes oscillating at different resonant frequencies are coupled through three-wave mixing in the presence of an auxiliary wave, and sharp transparency attributed to EIT effect is induced. We experimentally demonstrate the EIT effect using the metamaterial loaded with nonlinear capacitors in microwave region.