Article

# Classical Analogue of Electromagnetically Induced Transparency with a Metal-Superconductor Hybrid Metamaterial

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Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA.
(Impact Factor: 7.51). 07/2011; 107(4):043901. DOI: 10.1103/PhysRevLett.107.043901
Source: PubMed

ABSTRACT

Metamaterials are engineered materials composed of small electrical circuits producing novel interactions with electromagnetic waves. Recently, a new class of metamaterials has been created to mimic the behavior of media displaying electromagnetically induced transparency (EIT). Here we introduce a planar EIT metamaterial that creates a very large loss contrast between the dark and radiative resonators by employing a superconducting Nb film in the dark element and a normal-metal Au film in the radiative element. Below the critical temperature of Nb, the resistance contrast opens up a transparency window along with a large enhancement in group delay, enabling a significant slowdown of waves. We further demonstrate precise control of the EIT response through changes in the superfluid density. Such tunable metamaterials may be useful for telecommunication because of their large delay-bandwidth products.

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• "In order to realize practical applications, including the storage of electromagnetic waves, the tunability of the EIT-like effects is quite important. Many researchers have reported various methods to tune EIT-like metamaterials in a passive manner by changing the incident angles [39] [40] and in active manners by conductivity modulation utilizing diodes [41], superconductors [42] [43], and photo-carrier excitation in a semiconductor [44] [45], or by tuning an external magnetic field [36]. Recently, we proposed an EIT-like metamaterial whose properties can be controlled by applying bias voltages to diodes to change their capacitances, and we experimentally demonstrated the storage of electromagnetic waves in the microwave region [46]. "
##### Article: Implementation of Electromagnetically Induced Transparency in a Metamaterial Controlled with Auxiliary Waves
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ABSTRACT: We propose a metamaterial to realize true electromagnetically induced transparency (EIT), where the incidence of an auxiliary electromagnetic wave called the control wave induces transparency for a probe wave. The analogy to the original EIT effect in an atomic medium is shown through analytical and numerical calculations derived from a circuit model for the metamaterial. We performed experiments to demonstrate the EIT effect of the metamaterial in the microwave region. The width and position of the transparent region can be controlled by the power and frequency of the control wave. We also observed asymmetric transmission spectra unique to the Fano resonance.
Physical Review Applied 08/2015; 4(2):024013. DOI:10.1103/PhysRevApplied.4.024013
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• "Recently, these structures have been seriously sought to be utilized in metamaterial applications, not only because of their low-loss, but also for their deep subwavelength dimensions and tunability [1]. Various metamaterial schemes have been recently proposed and implemented based on both fully superconducting devices and in combination with normal conductors [2]–[7]. "
##### Article: High-Temperature Superconducting Spiral Resonator for Metamaterial Applications
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ABSTRACT: This work studies high-temperature superconducting spiral resonators as a viable candidate for realization of RF/microwave metamaterial atoms. The theory of superconducting spiral resonators will be discussed in detail, including the mechanism of resonance, the origin of higher order modes, the analytical framework for their determination, the effects of coupling scheme, and the dependence of the resonance quality factor and insertion loss on the parity of the mode. All the aforementioned models are compared with the experimental data from a micro-fabricated YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) spiral resonator. Moreover, the evolution of the resonance characteristics for the fundamental mode with variation of the operating temperature and applied RF power is experimentally examined, and its implications for metamaterial applications are addressed.
IEEE Transactions on Applied Superconductivity 06/2013; 23(3):1500304. DOI:10.1109/TASC.2012.2232343 · 1.24 Impact Factor
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• "The PIT behaviors achieved through these two approaches both result from destructive interference. So far most studies have been carried out to optimize the PIT effect by adapting the analysis mode, coupling, damping, absorption [18, 21–28], and active tuning [29] [30] "
##### Article: Broadband plasmon induced transparency in terahertz metamaterials
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ABSTRACT: Plasmon induced transparency (PIT) could be realized in metamaterials via interference between different resonance modes. Within the sharp transparency window, the high dispersion of the medium may lead to remarkable slow light phenomena and an enhanced nonlinear effect. However, the transparency mode is normally localized in a narrow frequency band, which thus restricts many of its applications. Here we present the simulation, implementation, and measurement of a broadband PIT metamaterial functioning in the terahertz regime. By integrating four U-shape resonators around a central bar resonator, a broad transparency window across a frequency range greater than 0.40 THz is obtained, with a central resonance frequency located at 1.01 THz. Such PIT metamaterials are promising candidates for designing slow light devices, highly sensitive sensors, and nonlinear elements operating over a broad frequency range.
Nanotechnology 05/2013; 24(21):214003. DOI:10.1088/0957-4484/24/21/214003 · 3.82 Impact Factor