Observing metamaterial induced transparency in individual Fano resonators with broken symmetry (original) (raw)
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Analogue of electromagnetically induced transparency in a terahertz metamaterial
Physical Review B, 2009
We experimentally demonstrate at terahertz frequencies that a planar metamaterial exhibits a spectral response resembling electromagnetically induced transparency. The metamaterial unit cell consists of a split ring surrounded by another closed ring where their dimensions are such that their excitable lowest order modes have identical resonance frequencies but very different lifetimes. Terahertz time-domain spectroscopy verifies that the interference of these two resonances results in a narrow transparency window located within a broad opaque region. In contrast to previous studies this enhanced transmission is achieved by independently exciting two resonances in which their coupling to the radiation field, and thus their linewidth, differs strongly. Rigorous numerical simulations prove that the transparency window is associated with a large group index and low losses, making the design potentially useful for slow light applications. This experiment opens an avenue to explore quantum-mechanical phenomena using localized resonances in metallic structures.
Applied Physics Letters, 2013
We experimentally demonstrate at terahertz frequencies that a planar metamaterial exhibits a spectral response resembling electromagnetically induced transparency. The metamaterial unit cell consists of a split ring surrounded by another closed ring where their dimensions are such that their excitable lowest order modes have identical resonance frequencies but very different life times. Terahertz time-domain spectroscopy verifies that the interference of these two resonances results in a narrow transparency window located within a broad opaque region. In contrast to previous studies this enhanced transmission is achieved by independently exciting two resonances in which their coupling to the radiation field, and thus their linewidth, differs strongly. Rigorous numerical simulations prove that the transparency window is associated with a large group index and low losses, making the design potentially useful for slow light applications. This experiment opens an avenue to explore quantum mechanical phenomena using localized resonances in metallic structures.
Electromagnetically induced transparency in a terahertz metamaterial
2010
We experimentally demonstrate a metamaterial that mimics electromagnetically induced transparency at terahertz frequencies. This is achieved by independently exciting two resonances in which their coupling to the radiation field, and thus their linewidth, differs strongly.
Manipulating the plasmon-induced transparency in terahertz metamaterials
Optics Express, 2011
Coupling between superradiant and subradiant mode resonators in a metamaterial unit cell plays an important role in observing the sharp transparency peak due to destructive interference between the resonators. This effect is enhanced as the resonators are brought closer to each other in a conventional planar arrangement. We present a novel coupling scheme of planar terahertz metamaterial to tune the plasmon-induced transparency peak by physically varying the distance between the superradiant and the subradiant resonators in such a way that the transparency peak begins to disappear as the coupled resonators are brought closer than a critical separation distance. The effect is attributed to the disappearance of the resonant behavior of the subradiant resonator in a closely coupled regime. The simple planar design presented here demonstrates a scheme to manipulate the electromagnetically induced transparency-like behavior in terahertz metamaterials and this could lead to the development of unique slow light devices for terahertz applications.
Journal of Applied Physics, 2018
We propose a scheme to achieve a dual-band electromagnetically induced transparency (EIT) effect in a planar terahertz metamaterial (MM), comprising an inner circular split ring resonator (CSRR) concentrically coupled to an outer asymmetric two-gap circular split ring resonator (ASRR). The scheme is numerically and theoretically analyzed. The dual-band EIT effect occurs as a result of the near field coupling between the resonant modes of the resonators comprising the MM configuration. It is observed that the dual-band EIT effect in the MM structure could be modulated with an in-plane rotation of the CSRR structure. The dual-band EIT effect is also examined by varying the asymmetry of the ASRR and the size of the inner CSRR. A theoretical model based upon the four-level tripod-system provides an intuitive explanation about the underlying coupling mechanism responsible for the dual-band EIT effect in the proposed MM structure. Our study could be significant in the development of multi-band slow light devices, narrowband absorbers, etc., in the terahertz regime.
Planar designs for electromagnetically induced transparency in metamaterials
Optics Express, 2009
We present a planar design of a metamaterial exhibiting electromagnetically induced transparency that is amenable to experimental verification in the microwave frequency band. The design is based on the coupling of a split-ring resonator with a cut-wire in the same plane. We investigate the sensitivity of the parameters of the transmission window on the coupling strength and on the circuit elements of the individual resonators, and we interpret the results in terms of two linearly coupled Lorentzian resonators. Our metamaterial designs combine low losses with the extremely small group velocity associated with the resonant response in the transmission window, rendering them suitable for slow light applications at room temperature.
Applied Physics Letters
We observe the excitation and tuning of electromagnetically induced transparency (EIT) by the interference between different excitation pathways of the dark mode in a planar terahertz metamaterial. The EIT unit cell consists of a cut wire as the bright resonator and a pair of split ring resonators (SRRs) as the dark element. The dark mode resonance is excited by both the electric and magnetic fields when the SRR pair translates along the wire without altering the lateral distance between the resonators. The electric and magnetic pathways of exciting the dark mode allows for a giant amplitude modulation of the EIT resonance.
Resonance phenomena in electromagnetic metamaterials for the terahertz domain: a review
Journal of Electromagnetic Waves and Applications, 2020
Most electromagnetic phenomena pertaining to metamaterials are observed at the resonance positions. In this review, we have collated and analyze the most prevalent forms of resonance-based phenomena observed in metamaterials to serve as a ready reference for future researchers. Our focus will be on metamaterials operating at the terahertz frequency domain. Starting with the origin and evolution of fundamental LC resonances in metamaterials, we would explain occurrence of typical even and odd higher order resonance modes. We have also discussed Fano resonances in asymmetric gap resonators-based metamaterials. Further, quantum phenomena analogues, such as, electromagnetically induced transparency (EIT) or Plasmon Induced Transparency (PIT), which can significantly influence the metamaterials resonances are also discussed. Thereafter, origins to ultra-sharp resonances in toroidal metamaterials, along with chiral metamaterials and resonance mode hybridization effects in the context of terahertz metamaterials are described. This review should be useful for undertaking.
Coupled-resonator-induced transparency
Physical Review A, 2004
We demonstrate that a cancellation of absorption occurs on resonance for two (or any even number of) coupled optical resonators, due to mode splitting and classical destructive interference, particularly when the resonator finesse is large and the loss in the resonator farthest from the excitation waveguide is small. The linewidth and group velocity of a collection of such coupled-resonator structures may be decreased by using larger resonators of equal size, by using larger resonators of unequal size where the optical path length of the larger resonator is an integer multiple of that of the smaller one, or by using a larger number of resonators per structure. We explore the analogy between these effects and electromagnetically-induced transparency in an atomic system.
Scientific Reports
The multiband transparency effect in terahertz (THz) domain has intrigued the scientific community due to its significance in developing THz multiband devices. In this article, we have proposed a planar metamaterial geometry comprised of a toroidal split ring resonator (TSRR) flanked by two asymmetric C resonators. The proposed geometry results in multi-band transparency windows in the THz region via strong near field coupling of the toroidal excitation with the dipolar C-resonators of the meta molecule. The geometry displays dominant toroidal excitation as demonstrated by a multipolar analysis of scattered radiation. High Q factor resonances of the metamaterial configuration is reported which can find significance in sensing applications. We report the frequency modulation of transparency windows by changing the separation between TSRR and the C resonators. The numerically simulated findings have been interpreted and validated using an equivalent theoretical model based upon three ...