Resonances of Closed Modes in Thin Arrays of Complex Particles

Prosvirnin, S. L.; Zouhdi, S.

doi:10.1007/978-94-007-1067-2_17

Cited by 53 publications

(52 citation statements)

References 11 publications

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“…Furthermore, conventional metamaterials are often composed of subwavelength particles that are simply unable to provide large-volume confinement of electromagnetic field necessary to support high-Q resonances. As recent theoretical analysis showed, high-Q resonances involving dark (or closed) modes are nevertheless possible in metamaterials if certain small asymmetries are introduced in the shape of their structural elements [7].In this Letter we report the observation of exceptionally narrow resonant responses in transmission and reflection of planar metamaterial achieved through introducing asymmetry into its structural elements. The appearance of narrow resonances is attributed to the excitation of otherwise forbidden anti-symmetric modes, that are weakly coupled to free-space ("dark modes").…”

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confidence: 75%

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confidence: 99%

“…electromagnetic modes that are weakly coupled to free-space. It is this property of the dark modes that allows in principal to achieve high quality resonances in very thin structures [7]. These modes are usually forbidden but can be excited in a planar metamaterial if, for example, its particles have certain structural asymmetry.…”

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Sharp Trapped-Mode Resonances in Planar Metamaterials with a Broken Structural Symmetry

Fedotov¹,

Rose²,

Prosvirnin³

et al. 2007

Phys. Rev. Lett.

1,083

792

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We report that resonant response with a very high quality factor can be achieved in a planar metamaterial by introducing symmetry breaking in the shape of its structural elements, which enables excitation of dark modes, i.e. modes that are weakly coupled to free space. The exotic and often dramatic physics predicted for metamaterials is underpinned by the resonant nature of their response and therefore achieving resonances with high quality factors is essential in order to make metamaterials' performance efficient. However, resonance quality factors (that is the resonant frequency over width of the resonance) demonstrated by conventional metamaterials are often limited to rather small values. This comes from the fact that resonating structural elements of metamaterials are strongly coupled to free-space and therefore suffer significant losses due to radiation. Furthermore, conventional metamaterials are often composed of subwavelength particles that are simply unable to provide large-volume confinement of electromagnetic field necessary to support high-Q resonances. As recent theoretical analysis showed, high-Q resonances involving dark (or closed) modes are nevertheless possible in metamaterials if certain small asymmetries are introduced in the shape of their structural elements [7].In this Letter we report the observation of exceptionally narrow resonant responses in transmission and reflection of planar metamaterial achieved through introducing asymmetry into its structural elements. The appearance of narrow resonances is attributed to the excitation of otherwise forbidden anti-symmetric modes, that are weakly coupled to free-space ("dark modes").Metamaterials that were used in our experiments consisted of identical sub-wavelength metallic "inclusions" structured in the form of asymmetrically split rings (ASR), which were arranged in a periodic array and placed on a thin dielectric substrate (see Fig. 1). ASRpatterns were etched from 35 µm copper cladding covering IS620 PCB substrate of 1.5 mm thickness. Each copper split ring had the radius of 6 mm and width of 0.8 mm and occupied a square translation cell of 15×15 mm (see Fig. 1). Such periodic structure does not diffract normal incident electromagnetic radiation for frequencies lower than 20 GHz. The overall size of the samples used were approximately 220 × 220 mm. Transmission and reflection of a single sheet of this meta-material were measured in an anechoic chamber under normal incidence conditions using broadband horn antennas. We studied structures with two different types of asymmetry designated as type A and B in Fig. 1. The rings of type A had two equal splits dividing them into pairs of arcs of different length corresponding to 140 and 160 deg (see Fig. 1A). The rings of type B were split along their diameter into two equal parts but had splits of different length corresponding to 10 and 30 deg (see Fig. 1B).

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Sharp Trapped-Mode Resonances in Planar Metamaterials with a Broken Structural Symmetry

Fedotov¹,

Rose²,

Prosvirnin³

et al. 2007

Phys. Rev. Lett.

1,083

792

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“…This anti-symmetric mode is a "trapped mode". It can be also observed when transmitting plane wave through asymmetric split ring resonators based metamaterial [9,10]. An antisymmetric mode cannot be excited with a source that is symmetric with respect to the resonator axis.…”

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confidence: 99%

“…Recently, a resonant response with a very high quality factor has been achieved in planar SRRs based metamaterials by introducing symmetry breaking in the shape of its structural elements [9,10].…”

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Tunable Trapped Mode in Symmetric Resonator Designed for Metamaterials

Ourir¹,

Abdeddaïm²,

Rosny³

2010

PIER

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Abstract-The excitation of an antisymmetric trapped mode on a symmetric metamaterial resonator is experimentally demonstrated. We use an active electronic device to break the electrical symmetry and therefore to generate this trapped mode on a symmetric spilt ring resonator. Even more, with such a tunable mode coupling resonator, we can precisely tune the resonant mode frequency. In this way, a shift of up to 15 percent is observed.

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Terahertz Metamaterials with Ultrahigh Angular Sensitivity

Born

Al-Naib

Jansen

et al. 2015

Advanced Optical Materials

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wileyonlinelibrary.com COMMUNICATIONfor angle of arrival (AoA) measurements [ 34 ] or as directional fi lters to shield detectors or detector arrays from scattered or refl ected light.The remainder of this work is structured as follows: To illustrate the proposed design principle, we will start with optimizing the angular sensitivity of a conventional asymmetric double split ring resonator (aDSR) metasurface as it is depicted in Figure 1 . [ 35,36 ] Next, the concept is applied to a multiband metamolecule. [37][38][39] We will demonstrate that the proposed design methodology allows for multiband high-Q fi lter structures, while the high angular sensitivity appears only for one of the resonances. Finally, we will present a detailed characterization of the multiband metasurface including a discussion on potential applications.As mentioned above, we will start with the aDSR geometry. In the context of our study, the size of the primitive cell ( p ), and the angle of incidence ( Θ ) for a given THz souvrce are the most important parameters. The relevant dimensions of the aDSR are given in the caption of Figure 1 and remain fi xed in the course of this study. In Figure 2 a, we simulated the transmission of the aDSR shown in Figure 1 between 0.44 and 0.52 THz and varied the size of the primitive cell between 280 and 340 µm.For small sizes of the primitive cell, the metasurface exhibits a sharp and distinct resonance. This mode is characterized by the collective out-of-phase oscillations of the opposing currents on each part of the resonator. They evoke very low radiation losses leading to a high Q-factor of the resonance, due to a strong interaction between neighboring unit cells. Because of the low radiation losses, such eigenmodes are also known as trapped-current modes or dark-modes. [ 35,40 ] In order to engineer the characteristics of this resonance, the asymmetry angle of the unit cell and the lattice constant are of relevance. Both parameters allow for the adjustment of the resonance depth, the Q-factor and the proximity to the dipole resonance. [ 35,41,42 ] An optimum value of the Q-factor can be observed at a period of p opt. = c/nf 0 , where c is the speed of light, n is the refractive index of the substrate, and f 0 is the resonance frequency. These fi ndings are in line with the results demonstrated by Singh et al., [ 41 ] who reported that metasurfaces consisting of split ring resonators exhibit maximal Q-factors under normal incidence when the size of the primitive cell p equals the resonance wavelength normalized with the refractive index of the substrate. At this condition, the 1 st diffracted order of the metamaterial grating is scattered into the resonator plane. [ 42 ] If the periodicity is increased to values larger than p opt. (crossing of the red line), the mode becomes evanescent, resulting in a much broader and less pronounced resonance.Yet besides this fi nding, we observe another interesting effect when the primitive unit cell approaches this threshold: As shown in Figure 2 c, the resonance be...

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Resonances of Closed Modes in Thin Arrays of Complex Particles

Abstract: Abstract. Numerical analysis of reflection properties of double-periodic two-element thin strip arrays is carried out. This analysis indicated extremely high quality band stop and band pass resonances appeared due to the excitation of non-symmetric current mode.

Cited by 53 publications

References 11 publications

Sharp Trapped-Mode Resonances in Planar Metamaterials with a Broken Structural Symmetry

Sharp Trapped-Mode Resonances in Planar Metamaterials with a Broken Structural Symmetry

Tunable Trapped Mode in Symmetric Resonator Designed for Metamaterials

Terahertz Metamaterials with Ultrahigh Angular Sensitivity

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