Sensing and slow light properties of dual-band terahertz metamaterials based on electromagnetically induced transparency-like

Abstract

Electromagnetically induced transparency (EIT) is a quantum interference phenomenon in a three-level atomic system. The generation of quantum interference effect significantly reduces the light absorptivity of the specific frequency that is strongly absorbed, and produces a sharp " transmission window" in the resonance absorption region. EIT is usually accompanied by strong dispersion, which significantly reduces the group velocity of light and enhances the nonlinear interaction. The EIT phenomenon of atomic system usually needs to be observed at very low temperature or high intensity laser, which is a very serious challenge for the application of EIT technology. The simulation of electromagnetically induced transparency using metamaterials can effectively break through these limitations.<br>In this paper, an electromagnetically induced transparent-like terahertz metamaterial structure with three bright modes is proposed and investigated. Two weakly hybrid states are composed of two bright modes with similar resonant frequencies. The energy between the two oscillates back and forth, and a transparent window is generated between the two resonance points. The designed metamaterial is composed of two groups of bright modes with adjacent resonant frequencies, and two groups of bright modes are coupled to produce two transparent windows. The formation mechanism of electromagnetically induced transparency-like is analyzed based on the simulation curve and electric field distribution. In addition, sensing properties of metamaterials is determined by simulation and calculation, and the refractive index sensitivity of the two windows can be as high as 451.92 GHz / RIU and 545.31 GHz / RIU under the optimal thickness of the measured substances. Through the sensing simulation of six petroleum products, it is verified that the dual-band has higher advantages in dielectric constant matching than the single frequency band. The characteristics of the designed metamaterial in the slow light effect are also studied. The maximum group delay of the two windows can reach 9.98 ps and 6.23 ps. Therefore, the structure is considered to have important application value in the field of high sensitivity sensors and slow light devices.

A high Q-factor metamaterial sensor based on electromagnetically induced transparency-like

“…Therefore, the dark mode is only indirectly excited by the bright mode. Owing to the significant dispersion properties and the narrow transparency window, the EITlike metamaterials have essential applications in optical switches [22,23], slow-light devices [24,25], sensors [26][27][28], and so on. Tian et al [29] numerically and experimentally demonstrated a high transmittance and lowlosses EIT-like metamaterial, whose unit structure is composed of two independent opening ring resonators.…”