Abstract
Electromagnetically induced transparency (EIT) is a quantum destructive interference phenomenon in three-level atomic systems, which can slow down the light velocity and has application prospects in information storage and processing. However, the EIT effect in atomic systems requires harsh experimental conditions. This problem can be solved by employing an EIT metamaterial, where destructive interference occurs between a bright mode and a dark mode or a quasi-dark mode, inducing a transparency window accompanied by the slow light effect. Here, we propose an actively mode tunable electromagnetically induced transparency terahertz metamaterial, which is comprised of a T-type resonator, a split-ring resonator (SRR), and coupled split-ring resonators (CSRRs). When the external electric field is vertical to the gap of the SRR (x-polarization), there is a single EIT mode accompanied by one slow light wave packet. On the other hand, when the external electric field is parallel to the gap of the SRR (y-polarization), there are two EIT modes accompanied by two slow light wave packets. Therefore, an active switch from a single EIT mode to dual EIT modes controlled by changing the polarization is demonstrated, which can find explanation from the electric field intensity distributions. This work offers a strategy to realize the mode tunable EIT, which may achieve potential applications in active filters, modulators, and slow light devices.
Highlights
Induced transparency (EIT) is a quantum destructive interference process that was first found in a threelevel atomic system,1 which forms a narrow transparency window in a broad absorption spectrum.2 it is accompanied by strong dispersion and large group velocity, leading to slow light3,4 and nonlinear effects.5,6 Electromagnetically induced transparency (EIT) has attracted much attention and shows great prospects in optical communication networks
When the incident light is x-polarized, the type resonator (TTR) acts as the bright mode, the coupled split-ring resonators (CSRRs) act as the quasi-dark mode, and the split-ring resonator (SRR) does not work
When the incident light is y-polarized, the TTR acts as the bright mode, the CSRRs act as the dark mode, and the SRR acts as the quasi-dark mode
Summary
Induced transparency (EIT) is a quantum destructive interference process that was first found in a threelevel atomic system, which forms a narrow transparency window in a broad absorption spectrum. it is accompanied by strong dispersion and large group velocity, leading to slow light and nonlinear effects. EIT has attracted much attention and shows great prospects in optical communication networks. Induced transparency (EIT) is a quantum destructive interference process that was first found in a threelevel atomic system, which forms a narrow transparency window in a broad absorption spectrum.2 It is accompanied by strong dispersion and large group velocity, leading to slow light and nonlinear effects.. As the development of metamaterials, the EIT effect can be realized by the destructive interference between a bright mode and a dark mode or a quasi-dark mode in metamaterials, operating at room temperature.. As the development of metamaterials, the EIT effect can be realized by the destructive interference between a bright mode and a dark mode or a quasi-dark mode in metamaterials, operating at room temperature.7–14 Based on this principle, various EIT metamaterials have been reported at frequencies in visible regimes, nearinfrared, terahertz (THz), and radio frequency, which are accompanied by the slow light effect and enhanced nonlinear interactions. This work paves the way toward designing compact and versatile slow light devices, which may achieve potential applications in the future THz communications
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