Discussion on slow light in magnetized plasma by electromagnetically induced transparency

Fenying Li, Mingyu Mao, Tao Zhang +3 more

In this paper, an electromagnetically induced transparency metamaterial simultaneously coupled with the incident electric and magnetic fields is designed and presented theoretically, whereas its reconfigurability, slow-wave effect, low-loss, and polarization insensitivity are analyzed and discussed principally. Based on the tunable solid-state plasma, there is a transmission peak with a 92.06% transmission at 0.544 THz in State 1 and a transmission peak with a 92.84% transmission at 0.7535 THz in State 2, thus achieving a frequency shift of 0.2085 THz. The maximum group delay, group index, and delay-bandwidth product in State 1 or 2, which are 723.7 ps or 494.7 ps, 1024.1 or 700.1, and 48.5 or 36.1, respectively, and the excellent slow-wave effects are discussed. In addition, the low-loss and polarization insensitivity are realized by rotating the split-ring resonators 180° and twisting the planar structure 90°. Considering the unique features of the designed metamaterial, it can be extensively applied to slow-light devices, communication, sensors, and nonlinear devices.

Xue Mei Su, Po Dong, Jinwei Gao +1 more

Jia Xin-juan, Yunbo Zhang

Guoqiang Wei, Qiuyue Nie, Zhonglin Zhang +4 more

Abstract Electromagnetically induced transparency (EIT), characterised by strong dispersion and a narrow transparency window, holds great potential for developing slow light devices in communications. However, in the GHz regime, achieving a simple EIT structure with high group delay and tunability remains challenging. This paper reports an asymmetric plasma waveguide capable of producing EIT analogues, as demonstrated by finite element method simulations and a two-oscillator model (TOM). The asymmetric plasma waveguide consists of a plasma–dielectric–plasma structure with non-uniformly sized teeth. The results indicate that the EIT analogue is attributed to detuning induced by the difference in tooth size. Specifically, the detuning creates an interference band, which governs the interaction between two bright modes (i.e. resonance modes in the two teeth). The TOM aligns excellently with numerical simulations. Notably, unlike previous works, the TOM is also analysed from a fundamental energy perspective. The operating frequency can be easily tuned by adjusting plasma frequencies. The maximum group delay can reach 8.5 ns. Our study advances the understanding of the EIT phenomenon in slot waveguides with asymmetric resonators and may offer a new platform for developing actively tunable microwave slow-light devices.

Wenzhuo Tang, Bin Luo, Yu Liu +1 more

Hai-Ning Ye, Bao-Fei Wan, Haifeng Zhang

The nonreciprocal and polarization-sensitive performances of analog of electromagnetically induced absorption (EIA-like) and electromagnetically induced transparency (EIT-like) effects are investigated by the transfer matrix method (TMM), and the layered topology metastructure containing microwave magnetized plasma is used to construct suitable bright resonators, dark resonators, and quasi-dark resonators. In the case of low frequencies, the incident TM wave fosters an evident nonreciprocal EIA-like effect, and its nonreciprocal absorptivity is higher than 0.8, while the EIA-like phenomenon fails to occur in the case of the incident TE wave. For the case of high-frequency incidence, the EIT-like and EIA-like effects can be switched by converting the TM wave into the TE one under the case of backward propagation, and the maximum nonreciprocal absorptivity can exceed 0.9 if the TE wave propagates. The effects of some critical variables such as incident angle, plasma frequency, plasma cyclotron frequency, and plasma layer thickness on nonreciprocal and polarization-sensitive characteristics have been explored, and the slow light property of the EIT-like effect has also been briefly involved, and its group refractive index can reach 1224. The energy level transition theory and the optimized two-oscillator model are also analyzed to explain the generation of EIA-like and EIT-like phenomena in depth. We hope that the relevant phenomena will be interesting for slow light devices, two-way communication of electromagnetic waves, and polarization separation devices.