Realistic metamaterial lenses: Limitations imposed by discrete structure

Lapine, Mikhail; Jelínek, Lukáš; Freire, Manuel J.; Marqués, R.

doi:10.1103/physrevb.82.165124

Cited by 25 publications

(15 citation statements)

References 31 publications

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“…1(a)) and it has strong impact on SNR, which is demonstrated in Ref. [15]. However, further improvement of the focusing property is difficult due to the MM loss [14,15].…”

Section: Modelingmentioning

confidence: 97%

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Proposal of Cylindrical Rolled-Up Metamaterial Lenses for Magnetic Resonance Imaging Application and Preliminary Experimental Demonstration

Xie¹,

Jiang²,

He³

2012

PIER

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Abstract-In this paper, we propose a cylindrical rolled-up negative permeability metamaterial (MM) lens for magnetic resonance imaging (MRI), and some analyses are given. The proposed cylindrical MM lens is fabricated by rolling a MM slab (constituted with capacitive-loaded copper split rings) into a tube that resembles a hollow ring. It can focus the field of a magnetic line source, which can increase the penetration depth and improve the sensitivity of a surface coil. The proposed cylindrical MM lens can also improve the discrimination of the signals coming from two independent sources. A clinical experiment is carried out in a General Electric Signa 1.5 T MRI system in order to verify the focusing ability of the proposed device.

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“…1(a)) and it has strong impact on SNR, which is demonstrated in Ref. [15]. However, further improvement of the focusing property is difficult due to the MM loss [14,15].…”

Section: Modelingmentioning

confidence: 97%

“…[15]. However, further improvement of the focusing property is difficult due to the MM loss [14,15]. The thickness of the lens (and thus the detection depth) is generally limited, and is restricted to near field detection.…”

Section: Modelingmentioning

confidence: 99%

Proposal of Cylindrical Rolled-Up Metamaterial Lenses for Magnetic Resonance Imaging Application and Preliminary Experimental Demonstration

Xie¹,

Jiang²,

He³

2012

PIER

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“…However, although asymmetries of crystalline lattices and their constiuent molecules often result in optical anisotropy of natural materials, it is very difficult to find the required values of optical anisotropy for a prescribed wavelength, in particular in the far-infrared and terahertz parts of the spectrum. On the contrary, metamaterials can be rationally designed to achieve optical anisotropy910111213141516171819 that can also be altered by changing the refractive index of the surrounding medium20212223 or by emplying electrical or thermal effects in liquid crystals2425. At the same time, substantial progress has been possible in developing metamaterials with unit cells reconfigurable with micro-actuators26272829303132333435.…”

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confidence: 99%

Microelectromechanical Maltese-cross metamaterial with tunable terahertz anisotropy

et al. 2012

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Dichroic polarizers and waveplates exploiting anisotropic materials have vast applications in displays and numerous optical components, such as filters, beamsplitters and isolators. Artificial anisotropic media were recently suggested for the realization of negative refraction, cloaking, hyperlenses, and controlling luminescence. However, extending these applications into the terahertz domain is hampered by a lack of natural anisotropic media, while artificial metamaterials offer a strong engineered anisotropic response. Here we demonstrate a terahertz metamaterial with anisotropy tunable from positive to negative values. It is based on the Maltese-cross pattern, where anisotropy is induced by breaking the four-fold symmetry of the cross by displacing one of its beams. The symmetry breaking permits the excitation of a Fano mode active for one of the polarization eigenstates controlled by actuators using microelectromechanical systems. The metamaterial offers new opportunities for the development of terahertz variable waveplates, tunable filters and polarimetry.

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“…Boundary effects have a remarkable effect in metamaterial applications, not only with regards to nonlinear processes , but also for linear applications such as magnetic resonance imaging, where the impact on the achievable resolution with negative‐permeability lenses largely depends on the boundary structure .…”

Section: Surface Effects and Strong Couplingmentioning

confidence: 99%

New degrees of freedom in nonlinear metamaterials

Lapine

2017

Phys. Status Solidi B

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This is an overview of the recent achievements in exploiting novel degrees of freedom in metamaterial design, which enable sophisticated nonlinear coupling mechanisms and bring enhancement to nonlinear behavior. One of the novel paradigms makes use of mechanical feedback, achieved by embedding electromagnetic resonators within elastic medium or engineering explicit elastic links between them, such as rotational feedback. These designs provide broad‐band self‐adjustable resonances, self‐oscillations, chaotic regimes, nonlinear chirality and, spontaneous chiral symmetry breaking. With this respect, a range of implementations has been analyzed, from flexible helices for microwaves to artificial electrostriction in optics. Another concept benefits from multi‐frequency operation, where the properties in completely distinct frequency ranges become entangled through specific metamaterial design –for example, direct optical coupling can be introduced between microwave resonators, providing an independent interaction channel. It was also found that hyperbolic metamaterials can bring notable benefits to classical nonlinear processes by imposing unusual phase matching solutions, with a rich choice of matching combinations. Finally, the boundary structure of metamaterials add yet another possibility to control their properties. Overall, the recent progress in these topics suggests a very positive outlook into the future of nonlinear metamaterials.

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Realistic metamaterial lenses: Limitations imposed by discrete structure

Cited by 25 publications

References 31 publications

Proposal of Cylindrical Rolled-Up Metamaterial Lenses for Magnetic Resonance Imaging Application and Preliminary Experimental Demonstration

Proposal of Cylindrical Rolled-Up Metamaterial Lenses for Magnetic Resonance Imaging Application and Preliminary Experimental Demonstration

Microelectromechanical Maltese-cross metamaterial with tunable terahertz anisotropy

New degrees of freedom in nonlinear metamaterials

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