An asymmetric metamaterial exhibiting an analog of double electromagnetically induced transparency (EIT) in the middle-infrared region is reported. The metamaterial consists of two-layered arrays of U-shaped rings embedded in a medium, with the lower layer rotated by 90°. Our simulations demonstrate that both maximum group indexes are extremely high at the two EIT-like positions. The group index reaches about thrice the currently reported maximum value at the high-frequency EIT-like position. The transmittance at the two transparency positions also possesses extremely high <i>Q</i> factors, which is conducive to controlling the propagation of electromagnetic waves.
© 2013 Chinese Optics Letters
An Yang, Changchun Yan, Jiebing Tian, Cheng Wang, Guiming Li, and Daohua Zhang, "An analog of double electromagnetically induced transparency with extremely high group indexes," Chin. Opt. Lett. 11, 051602- (2013)