Plasmon induced transparency in three dimensional magnetic meta-molecules

We report the first three-dimensional photonic metamaterial, an array of erected U-shape plasmonic gold meta-molecules, that exhibits plasmon induced transparency due to the magnetic field coupling between metamolecules. Using electron beam lithography with alignment technique , three erected U-shape gold nano rings are integrated in a unit cell with 6 00 nm periodicity both in x and y direction s, covering the total area of 75 ´ 75 µm 2 on a fused silica substrate. T he height of each gold nano ring is 110 nm. By introducing structural asymmetry, the magnetic field of the bright split ring resonator (SRR) couple to the other two dark SRRs result in an energy level splitting, which is similar with EIT-like spectra . A classical RLC circuit model was proposed to explain the coupling mechanism of EIT-like spectra .