Miniaturized terahertz stretchable electromagnetically induced transparency based on spoof surface plasmon polaritons

A miniaturized terahertz stretchable electromagnetically induced transparency (EIT) based on spoof surface plasmon polaritons (SPPs) is proposed in this paper. The terahertz EIT consists of one SPP-type dipole and a pair of split ring resonators (SRRs) on a stretchable polydimethylsiloxane substrate, where the SPP-type dipole and SRRs operate as the bright and dark modes, respectively. Owing to the slow-wave characteristics, the SPP-type dipole achieves compactness, and the dipole length decreases by approximately 38% compared to the conventional wire-type dipole. By mechanically stretching the EIT structure, the destructive interference between the bright and dark modes will be disturbed by the SRRs in the adjacent cells, resulting in different coupling strengths and thus affecting the EIT transmission spectra. When the stretchable factor increases by 30%, the EIT transmission increases from 0.15 to 0.58 (approximately four times amplitude modulation) at 0.4 THz, and the group delay ranges from 4.3 ps to 9.2 ps. Moreover, the compact EIT exhibits robust angular stability and almost maintains the same transmission at an oblique incident angle of 70°.