Electromagnetically induced transparency metamaterial with polarization independence and multi-transmission windows

In this paper, an electromagnetically induced transparency (EIT) metamaterial with the performances of polarization independence and multi-transmission windows is proposed. First, we design an EIT with a single transmission window, which is composed of an H-shaped structure and two split-ring resonators (SRRs). Then, by sequentially rotating the unit by 90°, a new EIT structure with rotational symmetry is obtained. The results show that the new EIT structure has the characteristics of polarization independence and multiple transmission windows, and each transmission window has a high maximum transmittance and group index. The first transmission window has a maximum group index of 88.9 and 98.9% maximum transmission. The maximum group indices of the second and third transmission windows are 117.9 and 215.3, and the peak transmissions are 89.9% and 97.4%, respectively. The multiple transmission windows with polarization independence widen the application scope of the proposed EIT metamaterial and are suitable for high-performance slow-wave devices with the above two requirements.