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Sample records for left-handed metamaterial lhm

  1. Magnetization of left-handed metamaterials

    International Nuclear Information System (INIS)

    Kourakis, I; Shukla, P K

    2006-01-01

    We propose a possible mechanism for the generation of magnetic fields in negative refraction index composite metamaterials. Considering the propagation of a high-frequency modulated amplitude electric field in a left-handed material (LHM), we show that the ponderomotive interaction between the field and low-frequency potential distributions leads to spontaneous generation of magnetic fields, whose form and properties are discussed

  2. Frequency Bandwidth Optimization of Left-Handed Metamaterial

    Science.gov (United States)

    Chevalier, Christine T.; Wilson, Jeffrey D.

    2004-01-01

    Recently, left-handed metamaterials (LHM s) have been demonstrated with an effective negative index of refraction and with antiparallel group and phase velocities for microwave radiation over a narrow frequency bandwidth. In order to take advantage of these characteristics for practical applications, it will be beneficial to develop LHM s with increased frequency bandwidth response and lower losses. In this paper a commercial three-dimensional electromagnetic simulation code is used to explore the effects of geometry parameter variations on the frequency bandwidth of a LHM at microwave frequencies. Utilizing an optimizing routine in the code, a geometry was generated with a bandwidth more than twice as large as the original geometry.

  3. Nonlinear left-handed transmission line metamaterials

    International Nuclear Information System (INIS)

    Kozyrev, A B; Weide, D W van der

    2008-01-01

    Metamaterials, exhibiting simultaneously negative permittivity ε and permeability μ, more commonly referred to as left-handed metamaterials (LHMs) and also known as negative-index materials, have received substantial attention in the scientific and engineering communities [1]. Most studies of LHMs (and electromagnetic metamaterials in general) have been in the linear regime of wave propagation and have already inspired new types of microwave circuits and devices. The results of these studies have already been the subject of numerous reviews and books. This review covers a less explored but rapidly developing area of investigation involving media that combine nonlinearity (dependence of the permittivity and permeability on the magnitude of the propagating field) with the anomalous dispersion exhibited by LHM. The nonlinear phenomena in such media will be considered on the example of a model system: the nonlinear left-handed transmission line. These nonlinear phenomena include parametric generation and amplification, harmonic and subharmonic generation as well as modulational instabilities and envelope solitons. (topical review)

  4. A Novel Tunable Triple-Band Left-Handed Metamaterial

    Directory of Open Access Journals (Sweden)

    Si Li

    2017-01-01

    Full Text Available A novel tunable triple-band left-handed metamaterial (LHM composed of a single-loop resonator (SLR and a variable capacitor-loaded short wire pair (CL-SWP printed on both sides of a substrate is presented in this paper. The CL-SWP-based metamaterial (MTM is a novel single-sided LHM. It is theoretically analyzed capable of extracting tunable negative permeability and a wide-band negative permittivity. We ran simulations for the CL-SWP-based MTM, the SLR-based MTM, and the proposed LHM. Together with the measured results, it is identified that this novel LHM exhibits a tunable triple-band left-handed (LH property. With the increase of the loaded capacitance, one LH band is relatively stable, while the other two are moving towards lower frequencies with their bandwidth getting wider and narrower, respectively. The surface current density distributions indicate that the first LH band is mainly decided by the SLR, one of the rest 2 LH bands is mainly decided by the CL-SWP, and the other one is decided by the SLR and CL-SWP together.

  5. A planar left-handed metamaterial based on electric resonators

    International Nuclear Information System (INIS)

    Chen Chun-Hui; Qu Shao-Bo; Wang Jia-Fu; Ma Hua; Wang Xin-Hua; Xu Zhuo

    2011-01-01

    A planar left-handed metamaterial(LHM) composed of electric resonator pairs is presented in this paper. Theoretical analysis, an equivalent circuit model and simulated results of a wedge sample show that this material exhibits a negative refraction pass-band around 9.6GHz under normal-incidence and is insensitive to a change in incidence angle. Furthermore, as the angle between the arm of the electric resonators and the strip connecting the arms increases, the frequency range of the pass-band shifts downwards. Consequently, this LHM guarantees a relatively stable torlerence of errors when it is practically fabricated. Moreover, it is a candidate for designing multi-band LHM through combining the resonator pairs with different angles. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  6. Flat Lens Focusing Demonstrated With Left-Handed Metamaterial

    Science.gov (United States)

    Wilson, Jeffrey D.; Schwartz, Zachary D.; Chevalier, Christine T.; Downey, Alan N.; Vaden, Karl R.

    2004-01-01

    Left-handed metamaterials (LHM's) are a new media engineered to possess an effective negative index of refraction over a selected frequency range. This characteristic enables LHM's to exhibit physical properties never before observed. In particular, a negative index of refraction should cause electromagnetic radiation to refract or bend at a negative angle when entering an LHM, as shown in the figure above on the left. The figure on the right shows that this property could be used to bring radiation to a focus with a flat LHM lens. The advantage of a flat lens in comparison to a conventional curved lens is that the focal length could be varied simply by adjusting the distance between the lens and the electromagnetic wave source. In this in-house work, researchers at the NASA Glenn Research Center developed a computational model for LHM's with the three-dimensional electromagnetic commercial code Microwave Studio, constructed an LHM flat lens, and used it to experimentally demonstrate the reversed refraction and flat lens focusing of microwave radiation.

  7. Left-Handed Metamaterials Studies and their Application to Accelerator Physics

    CERN Document Server

    Antipov, Sergey P; Liu Wan Ming; Power, John G

    2005-01-01

    Recently, there has been a growing interest in applying artificial materials, known as Left-Handed Metamaterials (LHM), to accelerator physics. These materials have both negative permittivity and permeability and therefore possess several unusual properties: the index of refraction is negative and the direction of the group velocity is antiparallel to the direction of the phase velocity (along k). These properties lead to a reverse Cherenkov effect, which has potential beam diagnostic applications, in addition to accelerator applications. Several LHM devices with different configurations are being experimentally and theoretically studied at Argonne. In this paper, we describe permittivity and permeability retrieval techniques that we have developed and applied to these devices. We have also investigated the possibility of building a Cherenkov detector based on LHM and propose an experiment to observe the reverse radiation generated by an electron beam passing through a LHM. The potential advantage of a LHM de...

  8. Two-Dimensional Simulation of Left-Handed Metamaterial Flat Lens Using Remcon XFDTD

    Science.gov (United States)

    Wilson, Jeffrey D.; Reinert, Jason M.

    2006-01-01

    Remcom's XFDTD software was used to model the properties of a two-dimensional left-handed metamaterial (LHM) flat lens. The focusing capability and attenuation of the material were examined. The results showed strong agreement with experimental results and theoretical predictions of focusing effects and focal length. The inherent attenuation in the model corresponds well with the experimental results and implies that the code does a reasonably accurate job of modeling the actual metamaterial.

  9. Refraction Characteristics of Cold Plasma Thin Film as a Left-Handed Metamaterial

    International Nuclear Information System (INIS)

    Sabah, Cumali

    2011-01-01

    A methodical analysis of refraction characteristics of a plane wave with any arbitrary polarization by a cold plasma thin film as a left-handed metamaterial (CPTF-LHM) which has simultaneously negative permittivity and permeability is presented. Numerical calculations are performed by the transfer matrix method using an in-house developed simulation program code. The results strongly recommend a possibility of manufacturing anti-reflection and/or total-transmission coatings and filters for a wide frequency range and/or by tuning the fraction of thickness of the CPTF-LHM. (fundamental areas of phenomenology(including applications))

  10. COMPORTAMIENTO DE METAMATERIAL (LHM Y CONVENCIONAL (RHM EN NANOESTRUCTURAS CILÍNDRICAS (NANOTUBOS METAMATERIAL (LHM AND CONVENTIONAL (RHM BEHAVIOR OF CYLINDRICAL NANOSTRUCTURES (NANOTUBES

    Directory of Open Access Journals (Sweden)

    María Ester Onell

    2009-08-01

    Full Text Available En este trabajo se estudia el comportamiento convencional o "Right Handed Materials" (RHM y el comportamiento de metamaterial o "Left Handed Materials" (LHM desde el punto de vista clásico, en nanoestructuras cilíndricas (nanotubos construidas imponiendo condiciones de borde a una red bidimensional infinita de circuitos LC acoplados con interacción a primeros vecinos. Tipificaremos los materiales considerando el signo del coseno del ángulo formado por los vectores velocidad de grupo y velocidad de fase, siendo metamaterial o LHM cuando el coseno del ángulo sea negativo y convencional o RHM cuando el valor del coseno sea positivo. El eje de los nanocilindros se hace coincidir, como primer caso, con la línea de transmisión dual, y como segundo caso, con la línea de transmisión directa. Este estudio muestra que ambos nanocilindros tienen un comportamiento de RHM y LHM, y además se comportan como filtros pasa alto y pasa bajo, pero ahora aparece un número discreto de frecuencias de corte en cada caso, a diferencia de lo que ocurre en las líneas de transmisión.This paper studies the behavior of conventional or "Right-Handed Materials" (RHM and "Left Handed Materials" (LHM also named metamaterial, of cylindrical nanostructures (nanotubes from the classical point of view. The nanotubes are building imposing boundary conditions in an infinite two-dimensional network of coupled LC circuits with interaction to nearest-neighbors. In this article, materials are classified considering the sign of the cosine of the angle between the group velocity vector and the phase velocity vector, in such a way that we have LHM behavior for negative cosine and we have RHM when the cosine is positive. The axis of the nanocylinders coincides, as the first case, with the dual transmission line, and as a second case, with the direct or conventional transmission line. This study shows that both nanocyinders have RHM and LHM behavior. In addition, it is found that

  11. Isotropic three-dimensional left-handed meta-materials

    OpenAIRE

    Koschny, Th.; Zhang, L.; Soukoulis, C. M.

    2005-01-01

    We investigate three-dimensional left-handed and related meta-materials based on a fully symmetric multi-gap single-ring SRR design and crossing continuous wires. We demonstrate isotropic transmission properties of a SRR-only meta-material and the corresponding left-handed material which possesses a negative effective index of refraction due to simultaneously negative effective permeability and permittivity. Minor deviations from complete isotropy are due to the finite thickness of the meta-m...

  12. Bright breathers in nonlinear left-handed metamaterial lattices

    Science.gov (United States)

    Koukouloyannis, V.; Kevrekidis, P. G.; Veldes, G. P.; Frantzeskakis, D. J.; DiMarzio, D.; Lan, X.; Radisic, V.

    2018-02-01

    In the present work, we examine a prototypical model for the formation of bright breathers in nonlinear left-handed metamaterial lattices. Utilizing the paradigm of nonlinear transmission lines, we build a relevant lattice and develop a quasi-continuum multiscale approximation that enables us to appreciate both the underlying linear dispersion relation and the potential for bifurcation of nonlinear states. We focus here, more specifically, on bright discrete breathers which bifurcate from the lower edge of the linear dispersion relation at wavenumber k=π . Guided by the multiscale analysis, we calculate numerically both the stable inter-site centered and the unstable site-centered members of the relevant family. We quantify the associated stability via Floquet analysis and the Peierls-Nabarro barrier of the energy difference between these branches. Finally, we explore the dynamical implications of these findings towards the potential mobility or lack thereof (pinning) of such breather solutions.

  13. Modeling of a Variable Focal Length Flat Lens Using Left Handed Metamaterials

    Science.gov (United States)

    Reinert, Jason

    2004-01-01

    Left Handed Metamaterials (LHM) were originally purposed by Victor Veselago in1968. These substances would allow a flat structure to focus electromagnetic (EM) waves because they have a negative index of refraction. A similar structure made from conventional materials, those with a positive index of refraction, would disperse the waves. But until recently, these structures have been purely theoretical because substances with both a negative permittivity and negative permeability, material properties necessary for a negative index of refraction, do not naturally exist, Recent developments have produced a structure composed of an array of thin wires and split ring resonators that shows a negative index of refraction. area smaller than a square wavelength. How small the area is can be determined by how perfectly the lens is polished and how pure the substance is that composes the lens. These lenses must also be curved for focusing to occur. The focal length is determined by the curvature of the lens and the material. On the other hand, a flat structure made from LHM would focus light because of the effect of a negative index of refraction in Snell s law. The focal length could also be varied by simply adjusting the distance of the lens from the source of radiation. This could create many devices that are adjustable to different situations in fields such as biomedical imaging and communication. the software package XFDTD which solves Maxwell s equations in the frequency domain as well as the time domain. The program used Drude models of materials to simulate the effect of negative permittivity and negative permeability. Because of this, a LHM can be simulated as a solid block of material instead of an array of wires and split ring resonators. After a flat lens is formed, I am to examine the focusing effect of the lens and determine if a higher resolution flat lens can be developed. Traditional lenses made from conventional materials cannot focus an EM wave onto an My

  14. Dual-band left-handed metamaterials fabricated by using tree-shaped fractal

    International Nuclear Information System (INIS)

    Xu He-Xiu; Wang Guang-Ming; Yang Zi-Mu; Wang Jia-Fu

    2012-01-01

    A method of fabricating dual-band left-handed metematerials (LHMs) is investigated numerically and experimentally by single-sided tree-like fractals. The resulting structure features multiband magnetic resonances and two electric resonances. By appropriately adjusting the dimensions, two left-handed (LH) bands with simultaneous negative permittivity and permeability are engineered and are validated by full-wave eigenmode analysis and measurement as well in the microwave frequency range. To study the multi-resonant mechanism in depth, the LHM is analysed from three different perspectives of field distribution analysis, circuit model analysis, and geometrical parameters evaluation. The derived formulae are consistent with all simulated results and resulting electromagnetic phenomena, indicating the effectiveness of the established theory. The method provides an alternative to the design of multi-band LHM and has the advantage of not requiring two individual resonant particles and electrically continuous wires, which in turn facilitates planar design and considerably simplifies the fabrication. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  15. Scattering of electromagnetic waves by a graphene-coated thin cylinder of left-handed metamaterial

    Science.gov (United States)

    Pashaeiadl, Hamid; Naserpour, Mahin; Zapata-Rodríguez, Carlos J.

    2018-04-01

    In this paper we explored the scattering behavior of thin cylinders made of LHM and coated by a monoatomic graphene layer. A spectral tunability of the resonance peaks is evidenced by altering the chemical potential of the graphene coating, a fact that occurs at any state of polarization of the incident plane wave in opposition to the case of scatterers of dielectric core. On the contrary, no invisibility condition can be satisfied for dielectric environments. A singular performance is also found for cylinders with permittivity and permeability near zero. Practical implementations of our results can be carried out in sensing and wave manipulation driven by metamaterials.

  16. Left-handed metamaterial using Z-shaped SRR for multiband application by azimuthal angular rotations

    Science.gov (United States)

    Mehedi Hasan, Md; Faruque, Mohammad Rashed Iqbal

    2017-04-01

    In this paper, a left-handed metamaterial is proposed for multiband applications analysed by azimuthal (xy-plane) angular (φ) rotations. The square resonators are split and a metal bar titled in a way that look like a z-shape split ring resonator structure that is angular sensitive. The metamaterial is designed on the epoxy resin fibre substrate material, which shows extended bandwidth approximately 47.5% of the applicable frequency from 2.0 to 14.0 GHz and the quality factor is 77.30. Finite integration technique based electromagnetic simulator computer simulation technology Microwave Studio is used to design, simulation, and analyses purposes. The demonstrate structure rotates from 0° to π /2 and every π /12 degree intervals in the xy-plane for analysing the effects on bandwidths, effective medium ratio and left-handed characteristics. However, the measured data are well complied with the simulated data by rotating the metamaterial at the above mentioned azimuthal angle.

  17. From solitons to rogue waves in nonlinear left-handed metamaterials.

    Science.gov (United States)

    Shen, Yannan; Kevrekidis, P G; Veldes, G P; Frantzeskakis, D J; DiMarzio, D; Lan, X; Radisic, V

    2017-03-01

    In the present work, we explore soliton and roguelike wave solutions in the transmission line analog of a nonlinear left-handed metamaterial. The nonlinearity is expressed through a voltage-dependent, symmetric capacitance motivated by recently developed ferroelectric barium strontium titanate thin-film capacitor designs. We develop both the corresponding nonlinear dynamical lattice and its reduction via a multiple scales expansion to a nonlinear Schrödinger (NLS) model for the envelope of a given carrier wave. The reduced model can feature either a focusing or a defocusing nonlinearity depending on the frequency (wave number) of the carrier. We then consider the robustness of different types of solitary waves of the reduced model within the original nonlinear left-handed medium. We find that both bright and dark solitons persist in a suitable parametric regime, where the reduction to the NLS model is valid. Additionally, for suitable initial conditions, we observe a rogue wave type of behavior that differs significantly from the classic Peregrine rogue wave evolution, including most notably the breakup of a single Peregrine-like pattern into solutions with multiple wave peaks. Finally, we touch upon the behavior of generalized members of the family of the Peregrine solitons, namely, Akhmediev breathers and Kuznetsov-Ma solitons, and explore how these evolve in the left-handed transmission line.

  18. Zeroth-order resonance phenomenon in an acoustic composite right/left-handed metamaterial resonator.

    Science.gov (United States)

    Kim, Wan-Gu; Kang, Hwi Suk; Yoon, Suk Wang; Lee, Kang Il

    2017-10-01

    This study proposes an acoustic theory that describes the resonance phenomena in a resonator made of acoustic composite right/left-handed (CRLH) metamaterials, and verifies it through numerical simulation. The established theory for a microwave CRLH metamaterial resonator is adapted to explain the resonance phenomena in an acoustic CRLH metamaterial resonator. In particular, attention is focused on the zeroth-order resonance phenomenon which has several interesting properties. When a resonator is composed of a CRLH metamaterial, a resonance with a flat acoustic field distribution may occur at one of the frequencies where the wavenumber becomes zero. This resonance is called zeroth-order resonance. Through numerical simulation, such unusual resonance phenomenon in acoustics is observed in more detail and the proposed theory is verified. The results of the theory and the numerical simulation clearly show that zeroth-order resonance can exist at those frequencies where the acoustic field distribution is flat due to infinite wavelength. It is also shown that the resonance frequency and the Q factor of this resonance depend on the boundary condition at both ends of the resonator, and they basically do not change even when the number of units is reduced or increased.

  19. A Printed Xi-Shaped Left-Handed Metamaterial on Low-Cost Flexible Photo Paper.

    Science.gov (United States)

    Ashraf, Farhad Bin; Alam, Touhidul; Islam, Mohammad Tariqul

    2017-07-05

    A Xi-shaped meta structure, has been introduced in this paper. A modified split-ring resonator (MSRR) and a capacitive loaded strip (CLS) were used to achieve the left-handed property of the metamaterial. The structure was printed using silver metallic nanoparticle ink, using a very low-cost photo paper as a substrate material. Resonators were inkjet-printed using silver nanoparticle metallic ink on paper to make this metamaterial flexible. It is also free from any kind of chemical waste, which makes it eco-friendly. A double negative region from 8.72 GHz to 10.91 GHz (bandwidth of 2.19 GHz) in the X-band microwave spectra was been found. Figure of merit was also obtained to measure any loss in the double negative region. The simulated result was verified by the performance of the fabricated prototype. The total dimensions of the proposed structure were 0.29 λ × 0.29 λ × 0.007 λ . It is a promising unit cell because of its simplicity, cost-effectiveness, and easy fabrication process.

  20. A simplified analytical approach to calculation of the electromagnetic behavior of left-handed metamaterials with a graded refractive index profile

    Directory of Open Access Journals (Sweden)

    Dalarsson N.

    2007-01-01

    Full Text Available We investigated the spectral properties of a new class of nanostructured artificial composite materials with tailored electromagnetic response, i.e. negative refractive index materials, also known as "left-handed" metamaterials. We analyzed structures incorporating both ordinary positive index media and negative refractive index metamaterials where the interface may be graded to an arbitrary degree. Utilizing a modified version of the Rosen-Morse function, we derived analytical expressions for the field intensity and spectral reflection and transmission through a graded interface between positive and negative index materials. We compared our results to numerical solutions obtained using the transfer matrix technique. .

  1. Left Handed Materials: A New Paradigm in Structured Electromagnetics

    International Nuclear Information System (INIS)

    Johri, Manoj; Paudyal, Harihar

    2010-05-01

    A new paradigm has emerged exhibiting reverse electromagnetic properties. Novel composite and micro-structured materials (metamaterials) have been designed to control electromagnetic radiation. Such substances have been called as Left Handed Material (LHM) with simultaneous negative permittivity and negative permeability and negative refractive index as well. Left handed materials are of importance because of their ability to influence the behavior of electromagnetic radiation and to display properties beyond those available in naturally occurring materials. Typically these are sub-wavelength artificial structures where the dimensions are very small compared to the working wavelength. These dimensions are normally of the order of λ/10 where λ is the wavelength of electromagnetic wave propagating in the material. Emergence of this new paradigm leads to some very interesting consequences, such as, to create lenses that are not diffraction limited, cloaking, sensors (chemical, biological and individual molecule), optical and radio communication. This new development in structured electromagnetic materials has had a dramatic impact on the physics, optics and engineering communities. (author)

  2. Design and analysis of doped left-handed materials

    International Nuclear Information System (INIS)

    Zhang Hongxin; Bao Yongfang; Chen Tianming; Lü Yinghua; Wang Haixia

    2008-01-01

    We devise three sorts of doped left-handed materials (DLHMs) by introducing inductors and capacitors into the traditional left-handed material (LHM) as heterogeneous elements. Some new properties are presented through finite-difference time-domain (FDTD) simulations. On the one hand, the resonance in the traditional LHM is weakened and the original pass band is narrowed by introducing inductors. On the other hand, the original pass band of the LHM can be shifted and a new pass band can be generated by introducing capacitors. When capacitors and inductors are introduced simultaneously, the resonance of traditional LHM is somewhat weakened and the number of original pass bands as well as its bandwidth can be changed

  3. The sensitivity of surface polaritons in LHM-antiferromagnetic waveguide sensors

    Energy Technology Data Exchange (ETDEWEB)

    El-Khozondar, Hala J., E-mail: hkhozondar@iugaza.edu [Electrical Engineering Department, Islamic University, P.O.Box 108, Gaza, Palestine (Country Unknown); Al-Sahhar, Zeyad I., E-mail: z_alsahhar@yahoo.com [Physics Department, Al-Aqsa University, Gaza, Palestine (Country Unknown); Shabat, Mohamad M., E-mail: shabat@iugaza.edu.ps [Physics Department, Islamic University, Gaza, Palestine (Country Unknown)

    2014-11-15

    A three-layer waveguide structure sensor consisting of LHMs film surrounded by dielectric cladding and antiferromagnetic substrate is proposed. Left-handed materials (LHMs) known as Metamaterials (MTMs) have simultaneous negative permeability and permittivity. The dispersion relation for the structure is derived for TE modes only. The sensitivity is calculated for surface waves at the interface between LHM film and dielectric layer. Two ranges of frequencies are chosen such that the Voigt permeability, μ{sub v}, is either negative or positive. The sensitivity is proven to be affected by different parameters including the film thickness, LHM parameters, and Voigt permittivity. The results show that the proposed structure is sensitive to small changes in the cladding indicating that the structure is working as a sensor with high sensitivity. The parameters at which maximum sensitivity occur are obtained. - Highlights: • The homogenous sensitivity is used to measure the sensitivity of the structure. • Sensitivity changes as the value of Voigt permittivity, μ{sub v}, changes sign. • The sensitivity is affected by the film thickness and the LHM parameters. • The three-layered sensor has high sensitivity and compact structure. • The parameters at which we achieved maximum sensitivity are obtained.

  4. Lunar Health Monitor (LHM)

    Science.gov (United States)

    Lisy, Frederick J.

    2015-01-01

    Orbital Research, Inc., has developed a low-profile, wearable sensor suite for monitoring astronaut health in both intravehicular and extravehicular activities. The Lunar Health Monitor measures respiration, body temperature, electrocardiogram (EKG) heart rate, and other cardiac functions. Orbital Research's dry recording electrode is central to the innovation and can be incorporated into garments, eliminating the need for conductive pastes, adhesives, or gels. The patented dry recording electrode has been approved by the U.S. Food and Drug Administration. The LHM is easily worn under flight gear or with civilian clothing, making the system completely versatile for applications where continuous physiological monitoring is needed. During Phase II, Orbital Research developed a second-generation LHM that allows sensor customization for specific monitoring applications and anatomical constraints. Evaluations included graded exercise tests, lunar mission task simulations, functional battery tests, and resting measures. The LHM represents the successful integration of sensors into a wearable platform to capture long-duration and ambulatory physiological markers.

  5. Transmission measurements of a new metamaterial sample with negative refraction index

    International Nuclear Information System (INIS)

    Sabah, C.; Cakmak, A.O.; Ozbay, E.; Uckun, S.

    2010-01-01

    We presented the microwave experiments with a new metamaterial composed of triangular split ring resonators (TSRRs) and wire strip at microwave regime. The transmission measurements were performed in free space for two LHM samples which have different number of TSRRs and wire strips. The experimental results show that the left-handed transmission peak stands in the frequency band where both the permittivity and permeability are negative. It is also observed that left-handed transmission band can be shifted if the number of TSRRs and wire strips are changed.

  6. Transmission measurements of a new metamaterial sample with negative refraction index

    Energy Technology Data Exchange (ETDEWEB)

    Sabah, C., E-mail: Sabah@Physik.uni-frankfurt.d [Johann Wolfgang Goethe-Universitaet, Physikalisches Institut, Max-von-Laue-Str.1, D-60438, Frankfurt am Main, Deutschland (Germany); Cakmak, A.O., E-mail: atilla@ee.bilkent.edu.t [Bilkent University, Ankara (Turkey); Ozbay, E., E-mail: ozbay@bilkent.edu.t [Bilkent University, Ankara (Turkey); Uckun, S., E-mail: savas@gantep.edu.t [University of Gaziantep, Gaziantep (Turkey)

    2010-07-15

    We presented the microwave experiments with a new metamaterial composed of triangular split ring resonators (TSRRs) and wire strip at microwave regime. The transmission measurements were performed in free space for two LHM samples which have different number of TSRRs and wire strips. The experimental results show that the left-handed transmission peak stands in the frequency band where both the permittivity and permeability are negative. It is also observed that left-handed transmission band can be shifted if the number of TSRRs and wire strips are changed.

  7. Scattering Forces within a Left-Handed Photonic Crystal.

    Science.gov (United States)

    Ang, Angeleene S; Sukhov, Sergey V; Dogariu, Aristide; Shalin, Alexander S

    2017-01-23

    Electromagnetic waves are known to exert optical forces on particles through radiation pressure. It was hypothesized previously that electromagnetic waves inside left-handed metamaterials produce negative radiation pressure. Here we numerically examine optical forces inside left-handed photonic crystals demonstrating negative refraction and reversed phase propagation. We demonstrate that even though the direction of force might not follow the flow of energy, the positive radiation pressure is maintained inside photonic crystals.

  8. The Left-Handed Writer.

    Science.gov (United States)

    Bloodsworth, James Gaston

    Contrary to the beliefs of many, right-handedness is not a single factor existing in almost all people, with a few exceptions termed left-handed: neither extreme exists independently of the other. During the first 4 years of life there is a period of fluctuation between right and left-handed dominance. Statistics and findings vary in determining…

  9. Study on an SRR-shaped left-handed material patch antenna

    Science.gov (United States)

    Song, X. H.; Chen, L. L.; Wu, C. H.; Yuan, Y. N.

    2011-03-01

    Left-handed material (LHM) is an artificial material. It has negative permittivity and negative permeability simultaneously and has attracted a great deal of attention in recent years. This paper investigates a patch antenna based on SRR-shaped left-handed material by using the method of finite difference time domain (FDTD). A patch antenna based on SRR and notches is designed by employing the traditional construction method; the results show that there exists a wave resonance state at 7.67 GHz, where its refraction index is close to - 1. The effect has greatly enhanced the electromagnetic wave's resonance intensity, and has improved the localized extent of the electromagnetic energy noticeably in such an LHM structure; besides, it can also enhance the radiation gain, broaden the frequency band, improve the impedance matching condition, and restrain the high harmonics.

  10. Infrared metasurface with tunable composite right/left-handed dispersion

    Science.gov (United States)

    Ma, Jie; Luo, Yi; Wu, Xuefei; Xu, Hongyan; Jing, Hongwei; Wu, Zhiming; Jiang, Yadong; Liu, Zhijun

    2017-11-01

    The distinctive dispersion of composite right/left-handed transmission-line metamaterial offers a unique way of manipulating electromagnetic waves across a wide spectral range from microwave to the infrared. In this paper, we present a tunable mid-infrared composite right/left-handed metasurface based on the phase-change material of vanadium dioxide. The metasurface consists of an array of ‘H’-shaped gold pads separated from a metallic ground plane by a film of vanadium dioxide. As the insulator-to-metal phase transition is thermally triggered, both right-handed and left-handed metasurface modes redshift with reduced absorbance before they are eventually switched off. The tunabilities of right-handed mode frequency and left-handed mode frequency are measured to be approximately 3.6% and 2.7%, respectively. Our demonstrated metasurface with tunable composite right/left-handed dispersion could be useful for beam scanning for a fixed frequency in mid-infrared applications.

  11. Sensitivity enhancement of a surface plasmon resonance sensor using porous metamaterial layers

    Science.gov (United States)

    Cherifi, Abdellatif; Bouhafs, Benamar

    2017-12-01

    In this work, the surface plasmon resonance (SPR) device with two porous left handed metamaterial (LHM) layers separated by an insulator gap, is investigated. The effect of the insulator gap thickness and its refractive index (RI) on the angular response of the device is analyzed. The results show that the sensitivity of the SPR sensor is enhanced compared to the standard SPR sensors. Here, the multilayer structure is probed with 738 nm-wavelength, and electromagnetic properties of active porous LHM layers are described from the effective medium theory (EMT). Furthermore, in the increase of the porosity from 0 to 0.6, the designed nanocavity exhibits a fundamental SPR mode long-range (LR) type and it can be of interest in high-performance SPR sensing.

  12. Surface polaritons in grating composed of left-handed materials

    Science.gov (United States)

    Tiwari, D. C.; Premlal, P. L.; Chaturvedi, Vandana

    2018-01-01

    In this work, we developed a unique mathematical model to solve dispersion relation for surface polaritons (SPs) in artificial composite materials grating. Here, we have taken two types of materials for analysis. In the first case, the grating composed of epsilon-negative (ENG) material and air interface. In second case, grating composed of left-handed materials (LHMs) and ENG medium interface is considered. The dispersion curves of both p and s polarized SPs modes are obtained analytically. In the case of ENG grating and air interface, polaritons dispersion curves exist for p-polarization only, whereas for LHM grating and ENG medium interface, the polaritons dispersion curves for both p and s polarization are observed.

  13. ARE LEFT HANDED SURGEONS LEFT OUT?

    OpenAIRE

    SriKamkshi Kothandaraman; Balasubramanian Thiagarajan

    2012-01-01

    Being a left-handed surgeon, more specifically a left-handed ENT surgeon, presents a unique pattern of difficulties.This article is an overview of left-handedness and a personal account of the specific difficulties a left-handed ENT surgeon faces.

  14. Time-domain electromagnetic energy in a frequency-dispersive left-handed medium

    International Nuclear Information System (INIS)

    Cui Tiejun; Kong Jinau

    2004-01-01

    From Maxwell's equations and the Poynting theorem, the time-domain electric and magnetic energy densities are generally defined in the frequency-dispersive media based on the conservation of energy. As a consequence, a general definition of electric and magnetic energy is proposed. Comparing with existing formulations of electric and magnetic energy in frequency-dispersive media, the new definition is more reasonable and is valid in any case. Using the new definition and staring from the equation of motion, we have shown rigorously that the total energy density and the individual electric and magnetic energy densities are always positive in a realistic artificial left-handed medium (LHM) [R. A. Shelby, D. R. Smith, and S. Schultz, Science 292, 77 (2001)], which obeys actually the Lorentz medium model, although such a LHM has negative permittivity and negative permeability simultaneously in a certain frequency range. We have also shown that the conservation of energy is not violated in LHM. The earlier conclusions can be easily extended to the Drude medium model and the cold plasma medium model. Through an exact analysis of a one-dimensional transient current source radiating in LHM, numerical results are given to demonstrate that the work done by source, the power flowing outwards a surface, and the electric and magnetic energy stored in a volume are all positive in the time domain

  15. Artificial magnetism and left-handed media from dielectric rings and rods

    Energy Technology Data Exchange (ETDEWEB)

    Jelinek, L [Department of Electromagnetic Field, Czech Technical University in Prague, 166 27-Prague (Czech Republic); Marques, R, E-mail: l_jelinek@us.e [Departamento de Electronica y Electromagnetismo, Universidad de Sevilla, 41012-Sevilla (Spain)

    2010-01-20

    It is shown that artificial magnetism with relatively large frequency bandwidth can be obtained from periodic arrangements of dielectric rings. Combined with dielectric rods, dielectric rings can provide 3D isotropic left-handed metamaterials which are an advantageous alternative to metallic split ring resonators (SRRs) and/or metallic wires when undetectability by low frequency external magnetic fields is desired. Furthermore it is shown that, unlike conventional SRRs, dielectric rings can also be combined with natural plasma-like media to obtain a left-handed metamaterial.

  16. Theoretical investigation of five-layer waveguide structure including two left-handed material layers for refractometric applications

    Science.gov (United States)

    Alkanoo, Anas A.; Taya, Sofyan A.

    2018-03-01

    A slab waveguide structure consisting of five layers is studied for optical sensing applications. The five-layer waveguide structure has a guiding dielectric film, two left-handed material (LHM) layers and two dielectric layers as a substrate and a cladding. The dispersion relation and the sensitivity to any change in the index of the analyte layer are derived. The sensitivity is explored with different parameters of the structure. It is found that the sensitivity of the proposed structure can be significantly improved with the increase of the index of the guiding layer and the decrease of the permittivity of the LHM layers. Moreover, it can be also improved with the increase of the thickness of the LHM layers.

  17. Left Handed Materials in Magnetic Nanocomposites

    Science.gov (United States)

    2003-07-01

    2003 University of Delaware All rights reservedXiao ONR Review - 6 Negative Index of Refraction Air(n0=1) RHM with n>0 ?i ?r Air(n0=1) LHM with nɘ...i ?r ɘ According to Snell’s Law: n n i r θ θ sin sin 0= Reversed refrection can be observed at interface between RHM and LHM. 1 July 2003© 2003...reservedXiao ONR Review - 18 Direct Prove of Negative Refraction Index in Open Space Negative refraction index can be proved by the fact the

  18. Left-handed Children in Singapore.

    Science.gov (United States)

    Gan, Linda

    1998-01-01

    Used teacher questionnaires to examine incidence of left-handedness in nearly 2,800 Singaporean children, racial differences in this left-handed population, and educational provisions in preschool and primary school. Findings indicated that 7.5% of preschoolers and 6.3% of primary children were left-handed, with a higher proportion being Chinese…

  19. The Left-Handed: "Their Sinister" History.

    Science.gov (United States)

    Costas, Elaine Fowler

    The history of left-handedness can provide teachers and parents a better understanding of left-handed children and give those children more pride in their difference. No child should be made to feel that he or she is abnormal because of using the left hand, although some specific instruction for these students is necessary in handwriting. Many…

  20. A Negative Index Metamaterial to Enhance the Performance of Miniaturized UWB Antenna for Microwave Imaging Applications

    Directory of Open Access Journals (Sweden)

    Md. Zulfiker Mahmud

    2017-11-01

    Full Text Available A new, compact planar wideband negative index metamaterial based on a modified split ring resonator (SRR is studied to enhance performance of ultrawideband antenna. A compact, metamaterial (MTM-inspired microstrip antenna is presented for microwave imaging system (MIS application. Two layers of left-handed metamaterial array (2 × 4 of the unit cell are placed on the radiating patch and the ground plane, respectively. Each left-handed metamaterial (LHM unit cell was constructed by modifying a square split ring resonator (SRR, resulting in negative permeability and permittivity with a stable negative refractive index. The results shows that it has a significant impact on the performance of conventional patch antenna in terms of transmission co-efficient, efficiency and low loss. Compared to antenna without LHM, it is shown that the bandwidth is significantly broadened up to a few megahertz and becomes more convergent leading to the achievement of desired properties for ultra-wideband (UWB applications leading to microwave imaging. The proposed MTM antenna structure is fabricated on commercially-available, flame-retardant material of size 26 × 22 × 1.6 mm3 with 4.6 dielectric constants, due to its low cost and convenience for making multilayer printed circuit boards (PCBs. The antenna achieves 3.1 GHz to 10.71 GHz of impedance bandwidth (−10 dB, which covers the full UWB band. The use of double-layer negative index MTM unit cells enhances UWB performance, and the improved radiation efficiency, nearly directional radiation pattern, acceptable gain, stable surface current and negative refractive index make this MTM antenna a suitable candidate for UWB applications.

  1. Metamaterials

    Science.gov (United States)

    Smith, David R.; Schurig, David; Starr, Anthony F.; Mock, Jack J.

    2014-09-09

    One exemplary metamaterial is formed from a plurality of individual unit cells, at least a portion of which have a different permeability than others. The plurality of individual unit cells are arranged to provide a metamaterial having a gradient index along at least one axis. Such metamaterials can be used to form lenses, for example.

  2. Metamaterials

    CERN Document Server

    Cui, Tie Jun

    2009-01-01

    Includes an introduction to optical transformation theory, revealing invisible cloaks, EM concentrators, beam splitters, and new-type antennas. This title offers a presentation of general theory on artificial metamaterials composed of periodic structures, and coverage of a rapid design method for inhomogeneous metamaterials.

  3. Vergisson 4: a left-handed Neandertal.

    Science.gov (United States)

    Condemi, Silvana; Monge, Janet; Quertelet, Sylvain; Frayer, David W; Combier, Jean

    2017-01-01

    Handedness is an important marker for lateralization of humans in the modern and fossil record. For the most part, Neandertals and their ancestors are strongly right-handed. We describe a single tooth from a Neandertal level at Vergisson 4 (Vg 4-83). This left upper central incisor shows all the features typical of Neandertal incisors. It also exhibits a predominance of left-handed striations. Striations on the incisor's labial surface were mapped at 20x magnification using Photoshop. Angulations of the striations were determined from their deviation from the maximum mesio-distal line and were analyzed using NIH's freeware, Image J. Of the 60 labial surface striations, Vg 4-83 shows a strong predominance of left-handed striations (46; 76.7%), which are statistically significantly different (p handed striations. The identification of another left-handed Neandertal adds to our understanding about handedness variation in this fossil hominin. Given the high frequency of right-handed Neandertals, the 90: 10 modern ratio is still preserved in this group. © 2016 Wiley Periodicals, Inc.

  4. Spatial Deficit in Familial Left-Handed Children.

    Science.gov (United States)

    And Others; Eme, Robert

    1978-01-01

    The study evaluated the hypothesis that familial left-handed children, who presumably have bilateral representation of language ability, should show an impairment in spatial abiblity on 44 children (22 right handed, 11 familial left handed, and 11 nonfamilial left handed) whose average age was 8 years old. (Author/PHR)

  5. Challenges training left-handed surgeons.

    Science.gov (United States)

    Anderson, Maia; Carballo, Erica; Hughes, David; Behrer, Christopher; Reddy, Rishindra M

    2017-09-01

    Being left-handed (LH) is considered a disadvantage in surgical training. We sought to understand the perspectives of LH trainees and surgical educators on the challenges and modifications in training LH surgeons. A survey was distributed to surgeons, surgical residents, and medical students about challenges teaching and learning surgical technique. 25 LH surgeons, 65 right-handed (RH) surgeons, and 39 LH trainees completed the survey. Compared to LH surgeons, RH surgeons reported more difficulty (46% vs 16%, p = 0.003) and less comfort teaching LH trainees (28% vs 4%, p = 0.002), and 10 (15%) reported that LH trainees have less technical ability. RH surgeons identified challenges translating technique to LH trainees and physical limitations of an environment optimized for right-handed mechanics. The disadvantage LH surgical trainees face is due to barriers in training rather than inherent lesser ability. Nonetheless, minimal modifications are made to overcome these barriers. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Enantioselective targeting left-handed Z-G-quadruplex.

    Science.gov (United States)

    Zhao, Andong; Zhao, Chuanqi; Ren, Jinsong; Qu, Xiaogang

    2016-01-25

    Herein, we report the first example where an M-enantiomer of a chiral metal complex can selectively stabilize a left-handed G-quadruplex, but its P-enantiomer cannot. The interactions between the chiral metal complexes and the left-handed G-quadruplex were evaluated by UV melting, circular dichroism, isothermal titration calorimetry, gel electrophoresis and NMR titrations.

  7. Left-Handed Students: A Forgotten Minority. Fastback 399.

    Science.gov (United States)

    Kelly, Evelyn B.

    This fastback, a booklet bound "left-handed," is designed to help educators become aware of the problems faced by left-handed students in school and to suggest ways that many of the problems might be solved. Following an introduction discussing a personal experience with left-handedness, the booklet continues with a brief history of the treatment…

  8. Left-Handed Children--Are They Losing Out?

    Science.gov (United States)

    Milsom, Lauren

    1995-01-01

    Discusses difficulties faced by left-handed children in everyday schoolwork. Highlights include right-handed bias of toys, clothing, and tools; the need for guidance in handwriting; problem areas including domestic science, arts and crafts, and metal and woodwork; left-hand advantages in sports and creative arts; and the European Left-Handers Club…

  9. Left-Handed Preschool Children with Orthopedic Disabilities.

    Science.gov (United States)

    Banham, Katharine M.

    1983-01-01

    The mental development of 332 preschool-age children with orthopedic disabilities was assessed at a children's hospital over a 10-year period, and comparisons were made for right-handed and left-handed. The left-handed children were slower than right-handed children in learning speech and language skills (Author/SEW)

  10. Left-handed materials in metallic magnetic granular composites

    International Nuclear Information System (INIS)

    Chui, S.T.; Lin, Z.F.; Hu, L.-B.

    2003-01-01

    There is recently interests in the 'left-handed' materials. In these materials the direction of the wave vector of electromagnetic radiation is opposite to the direction of the energy flow. We present simple arguments that suggests that magnetic composites can also be left-handed materials. However, the physics involved seems to be different from the original argument. In our argument, the imaginary part of the dielectric constant is much larger than the real part, opposite to the original argument

  11. Left-handed surgical instruments - a guide for cardiac surgeons.

    Science.gov (United States)

    Burdett, Clare; Theakston, Maureen; Dunning, Joel; Goodwin, Andrew; Kendall, Simon William Henry

    2016-08-19

    For ease of use and to aid precision, left-handed instruments are invaluable to the left-handed surgeon. Although they exist, they are not available in many surgical centres. As a result, most operating theatre staff (including many left-handers) have little knowledge of their value or even application. With specific reference to cardiac surgery, this article addresses the ways in which they differ, why they are needed and what is required - with tips on use.

  12. Magnetotunable left-handed FeSiB ferromagnetic microwires

    Czech Academy of Sciences Publication Activity Database

    Labrador, A.; Gómez-Polo, C.; Pérez-Landazábal, J.I.; Zablotskyy, Vitaliy A.; Ederra, I.; Gonzalo, R.; Badini-Confalonieri, G.; Vazquez, M.

    2010-01-01

    Roč. 35, č. 13 (2010), s. 2161-2163 ISSN 0146-9592 Institutional research plan: CEZ:AV0Z10100522 Keywords : ferromagnetic microwires * left - handed materials * ferromagnetic resonance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.316, year: 2010 http://www.opticsinfobase.org/abstract.cfm?uri=ol-35-13-2161

  13. Challenges left-handed students face in Kenyan girls' secondary ...

    African Journals Online (AJOL)

    The conclusion of this study provide evidence that there is need for Kenya government to rethink her initial and in-service special education needs' teacher training to include a module in left-handedness in order to equip all teachers to be able to identify and assist left-handed students to learn with least difficult.

  14. Atypical white matter microstructure in left-handed individuals.

    Science.gov (United States)

    McKay, Nicole S; Iwabuchi, Sarina J; Häberling, Isabelle S; Corballis, Michael C; Kirk, Ian J

    2017-05-01

    Information regarding anatomical connectivity in the human brain can be gathered using diffusion tensor imaging (DTI). Fractional anisotropy (FA) is the most commonly derived value, and reflects how strongly directional are the underlying tracts. Differences in FA are thus associated with differences in the underlying microstructure of the brain. The relationships between these differences in microstructure and functional differences in corresponding regions have also been examined. Previous studies have found an effect of handedness on functional lateralization in the brain and corresponding microstructural differences. Here, using tract-based spatial statistics to analyse DTI-derived FA values, we further investigated the structural white matter architecture in the brains of right- and left-handed males. We found significantly higher FA values for left-handed, relatively to right-handed, individuals, in all major lobes, and in the corpus callosum. In support of previous suggestions, we find that there is a difference in the microstructure of white matter in left- and right-handed males that could underpin reduced lateralization of function in left-handed individuals.

  15. Structure of a left-handed DNA G-quadruplex.

    Science.gov (United States)

    Chung, Wan Jun; Heddi, Brahim; Schmitt, Emmanuelle; Lim, Kah Wai; Mechulam, Yves; Phan, Anh Tuân

    2015-03-03

    Aside from the well-known double helix, DNA can also adopt an alternative four-stranded structure known as G-quadruplex. Implications of such a structure in cellular processes, as well as its therapeutic and diagnostic applications, have been reported. The G-quadruplex structure is highly polymorphic, but so far, only right-handed helical forms have been observed. Here we present the NMR solution and X-ray crystal structures of a left-handed DNA G-quadruplex. The structure displays unprecedented features that can be exploited as unique recognition elements.

  16. Controllable optical black hole in left-handed materials.

    Science.gov (United States)

    Bai, Qiang; Chen, Jing; Shen, Nian-Hai; Cheng, Chen; Wang, Hui-Tian

    2010-02-01

    Halting and storing light by infinitely decelerating its speed, in the absence of any form of external control, is extremely di+/-cult to imagine. Here we present a theoretical prediction of a controllable optical black hole composed of a planar left-handed material slab. We reveal a criterion that the effective round-trip propagation length in one zigzag path is zero, which brings light to a complete standstill. Both theory and ab initio simulation demonstrate that this optical black hole has degrees flexible controllability for the speed of light. Surprisingly, the ab initio simulations reveal that our scheme has degrees flexible controllability for swallowing, holding, and releasing light.

  17. Propagation properties of right-hand circularly polarized Airy-Gaussian beams through slabs of right-handed materials and left-handed materials.

    Science.gov (United States)

    Huang, Jiayao; Liang, Zijie; Deng, Fu; Yu, Weihao; Zhao, Ruihuang; Chen, Bo; Yang, Xiangbo; Deng, Dongmei

    2015-11-01

    The propagation of right-hand circularly polarized Airy-Gaussian beams (RHCPAiGBs) through slabs of right-handed materials (RHMs) and left-handed materials (LHMs) is investigated analytically and numerically with the transfer matrix method. An approximate analytical expression for the RHCPAiGBs passing through a paraxial ABCD optical system is derived on the basis of the Huygens diffraction integral formula. The intensity and the phase distributions of the RHCPAiGBs through RHMs and LHMs are demonstrated. The influence of the parameter χ0 on the propagation of RHCPAiGBs through RHM and LHM slabs is investigated. The RHCPAiGBs possess transverse-momentum currents, which shows that the physics underlying this intriguing accelerating effect is that of the combined contributions of the transverse spin and transverse orbital currents. Additionally, we go a step further to explore the radiation force including the gradient force and scattering force of the RHCPAiGBs.

  18. Garner-Interference in left-handed awkward grasping.

    Science.gov (United States)

    Eloka, Owino; Feuerhake, Felix; Janczyk, Markus; Franz, Volker H

    2015-07-01

    The Perception-Action Model (PAM) claims to provide a coherent interpretation of data from all areas of the visual neurosciences, most notably data from neuropsychological patients and from behavioral experiments in healthy people. Here, we tested two claims that are part of the core version of the PAM: (a) certain actions (natural, highly practiced, and right-handed) are controlled by the dorsal vision for action pathway, while other actions (awkward, unpracticed, or left-handed) are controlled by the ventral vision for perception pathway. (b) Only the dorsal pathway operates in an analytical fashion, being able to selectively focus on the task-relevant dimension of an object (Ganel and Goodale, Nature 426(6967):664-667, 2003). We show that one of these claims must be wrong: using the same test for analytical processing as Ganel and Goodale (2003), we found that even an action that should clearly be ventral (left-handed awkward grasping) shows analytical processing just as a dorsal task does (right-handed natural precision grasping). These results are at odds with the PAM and point to an inconsistency of the model.

  19. Left Hand Dominance Affects Supra-Second Time Processing

    Science.gov (United States)

    Vicario, Carmelo Mario; Bonní, Sonia; Koch, Giacomo

    2011-01-01

    Previous studies exploring specific brain functions of left- and right-handed subjects have shown variances in spatial and motor abilities that might be explained according to consistent structural and functional differences. Given the role of both spatial and motor information in the processing of temporal intervals, we designed a study aimed at investigating timing abilities in left-handed subjects. To this purpose both left- and right-handed subjects were asked to perform a time reproduction of sub-second vs. supra-second time intervals with their left and right hand. Our results show that during processing of the supra-second intervals left-handed participants sub-estimated the duration of the intervals, independently of the hand used to perform the task, while no differences were reported for the sub-second intervals. These results are discussed on the basis of recent findings on supra-second motor timing, as well as emerging evidence that suggests a linear representation of time with a left-to-right displacement. PMID:22028685

  20. Left-handed sperm removal by male Calopteryx damselflies (Odonata).

    Science.gov (United States)

    Tsuchiya, Kaori; Hayashi, Fumio

    2014-01-01

    Male genitalia in several insect species are asymmetry in right and left shape. However, the function of such asymmetric male genitalia is still unclear. We found that the male genitalia of the damselfly Calopteryx cornelia (Odonata: Calopterygidae) are morphologically symmetric just after emergence but asymmetric after reproductive maturation. Males remove rival sperm stored in the female bursa copulatrix (single spherical sac) and the following spermatheca (Y-shaped tubular sac) prior to their own ejaculation to prevent sperm competition. Males possess the aedeagus with a recurved head to remove bursal sperm and a pair of spiny lateral processes to remove spermathecal sperm. The right lateral process is less developed than the left, and sperm stored in the right spermathecal tube are rarely removed. Experiments involving surgical cutting of each lateral process demonstrated that only the left process functions in spermathecal sperm removal. Thus, males of C. cornelia are left-handed in their sperm removal behaviour at copulation.

  1. Raman spectroscopic study of left-handed Z-RNA

    International Nuclear Information System (INIS)

    Trulson, M.O.; Cruz, P.; Puglisi, J.D.; Tinoco, I. Jr.; Mathies, R.A.

    1987-01-01

    The solvent conditions that induce the formation of a left-handed Z form of poly[r(G-C)] have been extended to include 6.5 M NaBr at 35 0 C and 3.8 M MgCl 2 at room temperature. The analysis of the A → Z transition in RNA by circular dichroism (CD), 1 H and 31 P NMR, and Raman spectroscopy shows that two distinct forms of left-handed RNA exist. The Z/sub R/-RNA structure forms in high concentrations of NaBr and NaClO 4 and exhibits a unique CD signature. Z/sub D/-RNA is found in concentrated MgCl 2 and has a CD signature similar to the Z form of poly[d(G-C)]. Significant differences in the glycosyl angle and sugar pucker between Z-DNA and Z-RNA are suggested by the 16-cm -1 difference in the position of this band. The Raman evidence for structural difference between Z/sub D/- and Z/sub R/-RNA comes from two groups of bands: First, Raman intensities between 1180 and 1600 cm -1 of Z/sub D/-RNA differ from those for Z/sub R/-RNA, corroborating the CD evidence for differences in base-stacking geometry. Second, the phosphodiester stretching bands near 815 cm -1 provide evidence of differences in backbone geometry between Z/sub D-/ and Z/sub R/-RNA

  2. Raman spectroscopic study of left-handed Z-RNA.

    Science.gov (United States)

    Trulson, M O; Cruz, P; Puglisi, J D; Tinoco, I; Mathies, R A

    1987-12-29

    The solvent conditions that induce the formation of a left-handed Z form of poly[r(G-C)] have been extended to include 6.5 M NaBr at 35 degrees C and 3.8 M MgCl2 at room temperature. The analysis of the A----Z transition in RNA by circular dichroism (CD), 1H and 31P NMR, and Raman spectroscopy shows that two distinct forms of left-handed RNA exist. The ZR-RNA structure forms in high concentrations of NaBr and NaClO4 and exhibits a unique CD signature. ZD-RNA is found in concentrated MgCl2 and has a CD signature similar to the Z form of poly[d(G-C)]. The loss of Raman intensity of the 813-cm-1 A-form marker band in both the A----ZR-RNA and A----ZD-RNA transitions parallels the loss of intensity at 835 cm-1 in the B----Z transition of DNA. A guanine vibration that is sensitive to the glycosyl torsion angle shifts from 671 cm-1 in A-RNA to 641 cm-1 in both ZD- and ZR-RNA, similar to the B----Z transition in DNA in which this band shifts from 682 to 625 cm-1. Significant differences in the glycosyl angle and sugar pucker between Z-DNA and Z-RNA are suggested by the 16-cm-1 difference in the position of this band. The Raman evidence for structural difference between ZD- and ZR-RNA comes from two groups of bands: First, Raman intensities between 1180 and 1600 cm-1 of ZD-RNA differ from those for ZR-RNA, corroborating the CD evidence for differences in base-stacking geometry. Second, the phosphodiester stretching bands near 815 cm-1 provide evidence of differences in backbone geometry between ZD- and ZR-RNA.

  3. Why are some people left-handed? An evolutionary perspective

    Science.gov (United States)

    Llaurens, V.; Raymond, M.; Faurie, C.

    2008-01-01

    Since prehistoric times, left-handed individuals have been ubiquitous in human populations, exhibiting geographical frequency variations. Evolutionary explanations have been proposed for the persistence of the handedness polymorphism. Left-handedness could be favoured by negative frequency-dependent selection. Data have suggested that left-handedness, as the rare hand preference, could represent an important strategic advantage in fighting interactions. However, the fact that left-handedness occurs at a low frequency indicates that some evolutionary costs could be associated with left-handedness. Overall, the evolutionary dynamics of this polymorphism are not fully understood. Here, we review the abundant literature available regarding the possible mechanisms and consequences of left-handedness. We point out that hand preference is heritable, and report how hand preference is influenced by genetic, hormonal, developmental and cultural factors. We review the available information on potential fitness costs and benefits acting as selective forces on the proportion of left-handers. Thus, evolutionary perspectives on the persistence of this polymorphism in humans are gathered for the first time, highlighting the necessity for an assessment of fitness differences between right- and left-handers. PMID:19064347

  4. Technical modifications for laparoscopic cholecystectomy by the left-handed surgeon.

    Science.gov (United States)

    Herrero-Segura, Antonio; López-Tomassetti Fernández, Eudaldo M; Medina-Arana, Vicente

    2007-10-01

    There is a complete paucity of literature for left-handed surgeons. Some studies revealed that left-handed surgical residents have lesser operating skills and some surgeons have considered leaving surgery at some point in their career owing to laterality-related frustrations. Most important, whereas minimally invasive surgical techniques have had a profound impact on the treatment of diseased gallbladder, these procedures do not eliminate laterality related to the discomfort of left-handed surgeons. Usually, left-handed surgeons must teach themselves a procedure. They must make modifications and learn some technical tips to make a more comfortable, convenient, and safe intervention. The aim of this study was to describe some modifications made by a left-handed surgeon to perform 52 safe laparoscopic cholecystectomies with standard right-handed instruments in our hospital. These surgical steps could be used in a reproducible way to minimize the recurring difficulties of left-handed learners in a surgical residency program.

  5. Drilling simulated temporal bones with left-handed tools: a left-hander's right?

    Science.gov (United States)

    Torgerson, Cory S; Brydges, Ryan; Chen, Joseph M; Dubrowski, Adam

    2007-11-01

    Left-handed trainees can be at a disadvantage in the surgical environment because of a right-handed bias. The effectiveness of teaching left-handed trainees to use an otologic drill designed for their dominant hand versus the conventional right-handed drill was examined. Novice medical students were recruited from the university community. Twenty-four subjects were left-handed, and 12 were right-handed. Eight left-handed surgeons also participated. A randomized controlled trial was conducted to compare the performance of left-handed trainees using novel left-handed drills to that of left-handed trainees using right-handed tools and to that of right-handed trainees using right-handed tools. The evaluation consisted of 3 phases: pretest, skill acquisition, and 2 post-tests. The measurement tools included expert assessment of performance, and subjective and objective final product analyses. An initial construct validity phase was conducted in which validity of the assessment tools was ensured. Both the left-handers using left-handed tools and the right-handers using right-handed tools significantly outperformed the left-handers using right-handed tools at pretest, immediate posttest, and delayed posttest. All participants improved their performance as a function of practice. The left-handed trainees learned bone drilling better with tools designed for the left hand. These tools may be incorporated into residency training programs for the development of surgical technical skills. Future studies should assess skill transfer between the left-handed and right-handed drills.

  6. Hand Preference and Skill in 115 Children of Two Left-Handed Parents.

    Science.gov (United States)

    Annett, Marian

    1983-01-01

    Studied hand skill and performance in children (N=115) of left-handed parents using peg moving tasks and soccer kicks. Concluded that being raised by two left-handed parents does little to hinder the expression of the rs plus gene. Correlations for handedness in families depend more on genetics than experience. (Author/JAC)

  7. Metamaterial Inspired Microstrip Antenna Investigations Using Metascreens

    Directory of Open Access Journals (Sweden)

    Muhammad Tauseef Asim

    2015-01-01

    Full Text Available A dual layer periodically patterned metamaterial inspired antenna on a low cost FR4 substrate is designed, simulated, fabricated, and tested. The eigenmode dispersion simulations are performed indicating the left handed metamaterial characteristics and are tunable with substrate permittivity. The same metamaterial unit cell structure is utilized to fabricate a metascreen. This metascreen is applied below the proposed metamaterial antenna and next used as superstrate above a simple patch to study the effects on impedance bandwidth, gain, and radiation patterns. The experimental results of these antennas are very good and closely match with the simulations. More importantly, the resonance for the proposed metamaterial antenna with metascreen occurs at the left handed (LH eigenfrequency of the metamaterial unit cell structure. The measured −10 dB bandwidths are 14.56% and 22.86% for the metamaterial antenna with single and double metascreens, respectively. The metascreens over the simple patch show adjacent dual band response. The first and second bands have measured −10 dB bandwidths of 9.6% and 16.66%. The simulated peak gain and radiation efficiency are 1.83 dBi and 74%, respectively. The radiation patterns are also very good and could be useful in the UWB wireless applications.

  8. Functioning of medial olivocochlear bundle in right- and left-handed individuals.

    Science.gov (United States)

    Kaipa, Ramesh; Kumar, U Ajith

    2017-07-01

    Functional symmetry of medial olivocochlear bundle (MOCB) as a function of handedness remains to be well investigated. The current study aimed to assess the functional symmetry of MOCB through contralateral inhibition of otoacoustic emissions (OAEs) in right- and left-handed individuals. Thirteen left-handed and 13 right-handed individuals in the age range of 19-25 years participated. Behavioural experiment involved measuring speech perception in noise and vocal reaction time. Physiological experiment involved measuring the contralateral inhibition of OAEs in both the ears of participants. Findings of the current study revealed lack of functional asymmetry in right- as well as left-handed individuals. Results of the current study suggest that right- as well as left-handed individuals do not demonstrate functional asymmetry at the level of descending auditory pathways unlike the higher cortical centres.

  9. Assessment of speed of writing among left-handed and righthanded ...

    African Journals Online (AJOL)

    -handed undergraduates at University of Benin. One hundred (100) undergraduate students irrespective of gender were used. Fifty of the students were males while the remaining fifty were females. Fifty (50) were left-handed and fifty (50) were ...

  10. Superior Temporal Gyrus Volume Abnormalities and Thought Disorder in Left-Handed Schizophrenic Men

    Science.gov (United States)

    Holinger, Dorothy P.; Shenton, Martha E.; Wible, Cynthia G.; Donnino, Robert; Kikinis, Ron; Jolesz, Ferenc A.; McCarley, Robert W.

    2010-01-01

    Objective Studies of schizophrenia have not clearly defined handedness as a differentiating variable. Moreover, the relationship between thought disorder and anatomical anomalies has not been studied extensively in left-handed schizophrenic men. The twofold purpose of this study was to investigate gray matter volumes in the superior temporal gyrus of the temporal lobe (left and right hemispheres) in left-handed schizophrenic men and left-handed comparison men, in order to determine whether thought disorder in the left-handed schizophrenic men correlated with tissue volume abnormalities. Method Left-handed male patients (N=8) with DSM-III-R diagnoses of schizophrenia were compared with left-handed comparison men (N=10) matched for age, socioeconomic status, and IQ. Magnetic resonance imaging (MRI) with a 1.5-T magnet was used to obtain scans, which consisted of contiguous 1.5-mm slices of the whole brain. MRI analyses (as previously defined by the authors) included the anterior, posterior, and total superior temporal gyrus in both the left and right hemispheres. Results There were three significant findings regarding the left-handed schizophrenic men: 1) bilaterally smaller gray matter volumes in the posterior superior temporal gyrus (16% smaller on the right, 15% smaller on the left); 2) a smaller volume on the right side of the total superior temporal gyrus; and 3) a positive correlation between thought disorder and tissue volume in the right anterior superior temporal gyrus. Conclusions These results suggest that expression of brain pathology differs between left-handed and right-handed schizophrenic men and that the pathology is related to cognitive disturbance. PMID:10553736

  11. A Qualitative assessment of the impact of handedness among left-handed surgeons in Saudi Arabia.

    Science.gov (United States)

    Zaghloul, Mohamed S; Saquib, Juliann; Al-Mazrou, AbdulRahman; Saquib, Nazmus

    2018-01-01

    Among Muslims, the use of the left hand in daily activities is discouraged; many people believe that left-handed physicians lack the competency for surgery. The study aim was to document the experience of left-handed surgeons in Saudi Arabia and the impact of handedness on their training, job performance, collegial relationships, and career progression. This qualitative study included 9 left-handed physicians in various surgical specialties from 4 major hospitals in Al-Qassim, Saudi Arabia. Face-to-face interviews using a semi-structured questionnaire were conducted. Interview transcripts were analysed with Qualitative Content Analysis Method. Of the participants, 78% were male and the mean age was 40 years. Twenty-two per cent were consultants, 67% were specialists, and 11% were resident physicians. Participants reported the following: (a) a lack of training programmes specific to handedness in undergraduate and postgraduate medical training, (b) inconvenience while being assisted by a right-handed colleague, (c) stress, fatigue, and physical pain due to the use of right-handed instruments, and (d) training of the right hand being the most common adaptation technique for a left-handed surgeon. It was concluded that left-handed surgeons experience difficulty with right-handed instruments and right-handed colleagues during surgery. It is recommended that clinical curriculum incorporate hand-specific training in surgery.

  12. A Compact Via-free Composite Right/Left Handed Low-pass Filter with Improved Selectivity

    Science.gov (United States)

    Kumar, Ashish; Choudhary, Dilip Kumar; Chaudhary, Raghvendra Kumar

    2017-07-01

    In this paper, a compact via-free low pass filter is designed based on composite right/left handed (CRLH) concept. The structure uses open ended concept. Rectangular slots are etched on signal transmission line (TL) to suppress the spurious band without altering the performance and size of filter. The filter is designed for low pass frequency band with cut-off frequency of 3.5 GHz. The proposed metamaterial structure has several prominent advantages in term of selectivity up to 34 dB/GHz and compactness with average insertion loss less than 0.4 dB. It has multiple applications in wireless communication (such as GSM900, global navigation satellite system (1.559-1.610 GHz), GSM1800, WLAN/WiFi (2.4-2.49 GHz) and WiMAX (2.5-2.69 GHz)). The design parameters have been measured and compared with the simulated results and found excellent agreement. The electrical size of proposed filter is 0.14λ0× 0.11λ0 (where λ0 is free space wavelength at zeroth order resonance (ZOR) frequency 2.7 GHz).

  13. Planar chiral metamaterials for biosensing applications

    Science.gov (United States)

    Murugkar, Sangeeta; De Leon, Israel; Horton, Matthew; Qassim, Hammam; Leach, Jonathan; Boyd, Robert W.

    2013-02-01

    There has been a considerable effort recently in the development of planar chiral metamaterials. Owing to the lack of inversion symmetry, these materials have been shown to display interesting physical properties such as negative index of refraction and giant optical activity. However, the biosensing capabilities of these chiral metamaterials have not been fully explored. Ultrasensitive detection and structural characterization of proteins adsorbed on chiral plasmonic substrates was demonstrated recently using UV-visible circular dichroism (CD) spectroscopy. Second harmonic generation microscopy is an extremely sensitive nonlinear optical probe to investigate the chirality of biomaterials. In this study, we characterize the chiral response of chiral plasmonic metamaterials using second harmonic generation microscopy and CD spectroscopy. These planar chiral metamaterials, fabricated by electron-beam lithography, consist of right-handed and left-handed gold gammadions of length 400 nm and thickness 100nm, deposited on a glass substrate and arranged in a square lattice with a periodicity of 800nm.

  14. Bimanual proprioceptive performance differs for right- and left-handed individuals.

    Science.gov (United States)

    Han, Jia; Waddington, Gordon; Adams, Roger; Anson, Judith

    2013-05-10

    It has been proposed that asymmetry between the upper limbs in the utilization of proprioceptive feedback arises from functional differences in the roles of the preferred and non-preferred hands during bimanual tasks. The present study investigated unimanual and bimanual proprioceptive performance in right- and left-handed young adults with an active finger pinch movement discrimination task. With visual information removed, participants were required to make absolute judgments about the extent of pinch movements made to physical stops, either by one hand, or by both hands concurrently, with the sequence of presented movement extents varied randomly. Discrimination accuracy scores were derived from participants' responses using non-parametric signal detection analysis. Consistent with previous findings, a non-dominant hand/hemisphere superiority effect was observed, where the non-dominant hands of right- and left-handed individuals performed overall significantly better than their dominant hands. For all participants, bimanual movement discrimination scores were significantly lower than scores obtained in the unimanual task. However, the magnitude of the performance reduction, from the unimanual to the bimanual task, was significantly greater for left-handed individuals. The effect whereby bimanual proprioception was disproportionately affected in left-handed individuals could be due to enhanced neural communication between hemispheres in left-handed individuals leading to less distinctive separation of information obtained from the two hands in the cerebral cortex. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  15. Are there excitability changes in the hand motor cortex during speech in left-handed subjects?

    Science.gov (United States)

    Tokimura, Hiroshi; Tokimura, Yoshika; Arita, Kazunori

    2012-01-01

    Hemispheric dominance was investigated in left-handed subjects using single transcranial magnetic stimulation to assess the possible effect of forced change in the dominant hand. Single transcranial magnetic stimuli were delivered randomly over the hand area of the left or right motor cortex of 8 Japanese self-declared left-handed adult volunteers. Electromyographic responses were recorded in the relaxed first dorsal interosseous muscle while the subjects read aloud. Laterality quotient calculated by the Edinburgh Inventory ranged from -100 to -5.26 and laterality index calculated from motor evoked potentials ranged from -86.2 to 38.8. There was no significant correlation between laterality quotient and laterality index. Mean data values across all 8 subjects indicated significant increases only in the left hand. Our ratio analysis of facilitation of the hand motor potentials showed that 2 each of the 8 self-declared left-handers were right- and left-hand dominant and the other 4 were bilateral-hand dominant. Speech dominancy was localized primarily in the right cerebral hemisphere in left-handed subjects, but some individuals exhibited bilateral or left dominance, possibly attributable to the forced change of hand preference for writing in childhood. Our findings suggest changes in the connections between the speech and hand motor areas.

  16. Left-handed properties dependence versus the interwire distance in Fe-based microwires metastructures

    Directory of Open Access Journals (Sweden)

    Gabriel Ababei

    2016-05-01

    Full Text Available Experimental and theoretical investigations on the left-handed properties dependence versus the interwire distance of three new proposed Fe77.5Si7.5B15 glass coated microwires-based metastructures are presented. The left-handed characteristics of the metastructures were determined in the frequency range 8.2 ÷ 12 GHz and external d.c. magnetic fields ranging from 0 to 32 kA/m. The experimental results show that the electromagnetic losses of the metastructures increase with the decreasing of the interwire distance due to the increasing of the long-range dynamic dipole-dipole interaction within inter-wires in the presence of the microwave field. The numerical calculations using Nicolson–Weiss–Ross algorithm are in agreement with the experimental results. The variation of the interwire distance proves to be a useful tool to obtain metastructures with controlled left-handed characteristics.

  17. Neural Model for Left-Handed CPW Bandpass Filter Loaded Split Ring Resonator

    Science.gov (United States)

    Liu, Haiwen; Wang, Shuxin; Tan, Mingtao; Zhang, Qijun

    2010-02-01

    Compact left-handed coplanar waveguide (CPW) bandpass filter loaded split ring resonator (SRR) is presented in this paper. The proposed filter exhibits a quasi-elliptic function response and its circuit size occupies only 12 × 11.8 mm2 (≈0.21 λg × 0.20 λg). Also, a simple circuit model is given and the parametric study of this filter is discussed. Then, with the aid of NeuroModeler software, a five-layer feed-forward perceptron neural networks model is built up to optimize the proposed filter design fast and accurately. Finally, this newly left-handed CPW bandpass filter was fabricated and measured. A good agreement between simulations and measurement verifies the proposed left-handed filter and the validity of design methodology.

  18. Dark localized structures in a cavity filled with a left-handed material

    International Nuclear Information System (INIS)

    Tlidi, Mustapha; Kockaert, Pascal; Gelens, Lendert

    2011-01-01

    We consider a nonlinear passive optical cavity filled with left-handed and right-handed materials and driven by a coherent injected beam. We assume that both left-handed and right-handed materials possess a Kerr focusing type of nonlinearity. We show that close to the zero-diffraction regime, high-order diffraction allows us to stabilize dark localized structures in this device. These structures consist of dips in the transverse profile of the intracavity field and do not exist without high-order diffraction. We analyze the snaking bifurcation diagram associated with these structures. Finally, a realistic estimation of the model parameters is provided.

  19. Dark localized structures in a cavity filled with a left-handed material

    Energy Technology Data Exchange (ETDEWEB)

    Tlidi, Mustapha [Optique non lineaire theorique, Universite Libre de Bruxelles, CP 231, Campus Plaine, B-1050 Bruxelles (Belgium); Kockaert, Pascal [OPERA-photonique, Universite Libre de Bruxelles, CP 194/5, 50, Av. F. D. Roosevelt, B-1050 Bruxelles (Belgium); Gelens, Lendert [Applied Physics Research Group (APHY), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel (Belgium)

    2011-07-15

    We consider a nonlinear passive optical cavity filled with left-handed and right-handed materials and driven by a coherent injected beam. We assume that both left-handed and right-handed materials possess a Kerr focusing type of nonlinearity. We show that close to the zero-diffraction regime, high-order diffraction allows us to stabilize dark localized structures in this device. These structures consist of dips in the transverse profile of the intracavity field and do not exist without high-order diffraction. We analyze the snaking bifurcation diagram associated with these structures. Finally, a realistic estimation of the model parameters is provided.

  20. Programming of left hand exploits task set but that of right hand depends on recent history.

    Science.gov (United States)

    Tang, Rixin; Zhu, Hong

    2017-07-01

    There are many differences between the left hand and the right hand. But it is not clear if there is a difference in programming between left hand and right hand when the hands perform the same movement. In current study, we carried out two experiments to investigate whether the programming of two hands was equivalent or they exploited different strategies. In the first experiment, participants were required to use one hand to grasp an object with visual feedback or to point to the center of one object without visual feedback on alternate trials, or to grasp an object without visual feedback and to point the center of one object with visual feedback on alternating trials. They then performed the tasks with the other hand. The result was that previous pointing task affected current grasping when it was performed by the left hand, but not the right hand. In experiment 2, we studied if the programming of the left (or right) hand would be affected by the pointing task performed on the previous trial not only by the same hand, but also by the right (or left) hand. Participants pointed and grasped the objects alternately with two hands. The result was similar with Experiment 1, i.e., left-hand grasping was affected by right-hand pointing, whereas right-hand grasping was immune from the interference from left hand. Taken together, the results suggest that when open- and closed-loop trials are interleaved, motor programming of grasping with the right hand was affected by the nature of the online feedback on the previous trial only if it was a grasping trial, suggesting that the trial-to-trial transfer depends on sensorimotor memory and not on task set. In contrast, motor programming of grasping with the left hand can use information about the nature of the online feedback on the previous trial to specify the parameters of the movement, even when the type of movement that occurred was quite different (i.e., pointing) and was performed with the right hand. This suggests that

  1. Enhanced localization of Dyakonov-like surface waves in left-handed materials

    DEFF Research Database (Denmark)

    Crasovan, L. C.; Takayama, O.; Artigas, D.

    2006-01-01

    We address the existence and properties of hybrid surface waves forming at interfaces between left-handed materials and dielectric birefringent media. The existence conditions of such waves are found to be highly relaxed in comparison to Dyakonov waves existing in right-handed media. We show...... that left-handed materials cause the coexistence of several surface solutions, which feature an enhanced degree of localization. Remarkably, we find that the hybrid surface modes appear for large areas in the parameter space, a key property in view of their experimental observation....

  2. Cued Dichotic Listening with Right-Handed, Left-Handed, Bilingual and Learning-Disabled Children.

    Science.gov (United States)

    Obrzut, John E.; And Others

    This study used cued dichotic listening to investigate differences in language lateralization among right-handed (control), left handed, bilingual, and learning disabled children. Subjects (N=60) ranging in age from 7-13 years were administered a consonant-vowel-consonant dichotic paradigm with three experimental conditions (free recall, directed…

  3. Aortic root and proximal aortic arch replacement (performed by a left-handed surgeon).

    Science.gov (United States)

    Carrel, Thierry

    2017-01-01

    We present our standard technique of composite graft replacement performed by a left-handed surgeon. This procedure is performed with a 30-day mortality comparable to that of elective isolated aortic valve replacement. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  4. The study of radiosensitivity in left handed compared to right handed healthy women.

    Science.gov (United States)

    Khosravifarsani, Meysam; Monfared, Ali Shabestani; Akhavan-Niaki, Haleh; Moslemi, Dariush; Hajian-Tilaki, Karimollah; Elahimanesh, Farideh; Borzoueisileh, Sajad; Seyfizadeh, Nayer; Amiri, Mehrangiz

    2012-08-24

    Radiosensitivity is an inheriting trait that mainly depends on genetic factors. it is well known in similar dose of ionizing radiation and identical biological characteristics 9-10 percent of normal population have higher radiation response. Some reports indicate that distribution of breast cancer, immune diseases including autoimmune diseases as example lupus, Myasthenia Gravies and even the rate of allergy are more frequent in left handed individuals compared to right handed individuals. The main goal of the present study is determination of radiosensitivity in left handed compared to right handed in healthy women by cytokinesis blocked micronuclei [CBMN] assay.5 ml peripheral fresh blood sample was taken from 100 healthy women including 60 right handed and 40 left handed. The age of participants was between 20-25 old years and they had been matched by sex. After blood sampling, blood samples were divided to 2 groups including irradiated and non-irradiated lymphocytes that irradiated lymphocytes were exposed to 2 Gy CO-60 Gama rays source then chromosomal aberrations was analyzed by CBMN [Cytokinesis Blocked Micronuclei Assay]. Our results have shown radiosensitivity index [RI] in left-handers compared to right-handers is higher. Furthermore, the mean MN frequency is elevated in irradiated lymphocytes of left-handers in comparison with right-handers. Our results from CBMN assay have shown radiosensitivity in the left handed is higher than right handed women but more attempts need to prove this hypothesis.

  5. A Left Handed Compliment: A newly discovered, early nineteenth-century lithograph by John Lewis Marks.

    Science.gov (United States)

    McManus, I C; Snowman, Janet

    2010-01-01

    A newly discovered, early nineteenth-century lithograph by John Lewis Marks (b. ca. 1795-1796, d. ca. 1857-1861), entitled A Left Handed Compliment, is described. In this humorous print a young boy is using his left hand to draw the face of an elderly woman who is his grandmother, and she is shocked at the boy's suggestion that he will, “just see if I can't touch off your old Phizog left handed”. The source of the joke about the left-handed compliment is obscure, but more than likely it is sexual in origin. Glued to the verso of the print are early versions of two prints by Robert Seymour (1798-1836), the illustrator of Dickens' Pickwick Papers, suggesting a possible link between Marks and Seymour. From the hatch patterns on the Seymour engravings, it appears that Seymour may himself have been left-handed and perhaps therefore the butt of the joke. An alternative possibility is that Phizog is a reference to Dickens' later illustrator whose pseudonym was Phiz. It is also just conceivable that the young boy is Marks's own young son, Jacob. The print can be placed in the context of a scatological English vernacular humour that extends from Shakespeare through to Donald McGill and into the present day.

  6. Evidence for right-hand feeding biases in a left-handed population.

    Science.gov (United States)

    Flindall, Jason W; Stone, Kayla D; Gonzalez, Claudia L R

    2015-05-01

    We have recently shown that actions with similar kinematic requirements, but different end-state goals may be supported by distinct neural networks. Specifically, we demonstrated that when right-handed individuals reach-to-grasp food items with intent to eat, they produce smaller maximum grip apertures (MGAs) than when they grasp the same item with intent to place it in a location near the mouth. This effect was restricted to right-handed movements; left-handed movements showed no difference between tasks. The current study investigates whether (and to which side) the effect may be lateralized in left-handed individuals. Twenty-one self-identified left-handed participants grasped food items of three different sizes while grasp kinematics were captured via an Optotrak Certus motion capture array. A main effect of task was identified wherein the grasp-to-eat action generated significantly smaller MGAs than did the grasp-to-place action. Further analysis revealed that similar to the findings in right-handed individuals, this effect was significant only during right-handed movements. Upon further inspection however, we found individual differences in the magnitude and direction of the observed lateralization. These results underscore the evolutionary significance of the grasp-to-eat movement in producing population-level right-handedness in humans as well as highlighting the heterogeneity of the left-handed population.

  7. Operate a 10-Key Adding Machine with My Left Hand? Sure! Student's Manual and Instructor's Handbook.

    Science.gov (United States)

    Wells, Frances

    Supporting performance objective 70 of the V-TECS (Vocational-Technical Education Consortium of States) Paying and Receiving Bankteller Catalog, this module includes both a set of student materials and an instructor's manual on using the 10-key adding machine with the left hand. (This module is the first in a set of eight on banktelling, [CE 019…

  8. A Left-Hand Rule for Faraday's Law

    Science.gov (United States)

    Salu, Yehuda

    2014-01-01

    A left-hand rule for Faraday's law is presented here. This rule provides a simple and quick way of finding directional relationships between variables of Faraday's law without using Lenz's rule.

  9. Self-supported all-metal THz metamaterials

    Science.gov (United States)

    Moser, H. O.; Jian, L. K.; Chen, H. S.; Bahou, M.; Kalaiselvi, S. M. P.; Virasawmy, S.; Maniam, S. M.; Cheng, X. X.; Heussler, S. P.; bin Mahmood, Shahrain; Wu, B.-I.

    2009-08-01

    Ideal metamaterials would consist of metal conductors only that are necessary for negative ɛ and μ. However, most of present-day metamaterials include dielectrics for various support functions. Overcoming dielectrics, we manufactured free-standing THz metamaterials as bi-layer chips of S-string arrays suspended by window-frames at a small gap that controls the resonance frequency. Remaining problems concerning their useful range of incidence angles and the possibility of stacking have been solved by manufacturing the first self-supported free-standing all-metal metamaterials featuring upright S-strings interconnected by metal rods. Large-area slabs show maximum magnetic coupling at normal incidence with left-handed resonances between 3.2 - 4.0 THz. Such metamaterials which we dub the meta-foil represent an ideal platform for including index-gradient optics to achieve optical functionalities like beam deflection and imaging.

  10. Metamaterial Sensors

    Directory of Open Access Journals (Sweden)

    Jing Jing Yang

    2013-01-01

    Full Text Available Metamaterials have attracted a great deal of attention due to their intriguing properties, as well as the large potential applications for designing functional devices. In this paper, we review the current status of metamaterial sensors, with an emphasis on the evanescent wave amplification and the accompanying local field enhancement characteristics. Examples of the sensors are given to illustrate the principle and the performance of the metamaterial sensor. The paper concludes with an optimistic outlook regarding the future of metamaterial sensor.

  11. Dielectric Metamaterials

    Science.gov (United States)

    2015-05-29

    Final Report  29 May 2015 Dielectric Metamaterials SRI Project P21340 ONR Contract N00014-12-1-0722 Prepared by: Srini Krishnamurthy...2 2. Theory of Metamaterials ....................................................................................................... 2 2.1...accurately assess the impact of various forms of disorder on metamaterials (MMs) (both dielectric and metal inclusions); and (5) identify designs

  12. Left-handed helical polymer resin nanotubes prepared by using N-palmitoyl glucosamine.

    Science.gov (United States)

    Li, Jiangang; Li, Yi; Li, Baozong; Yang, Yonggang

    2017-12-20

    Although the preparation of single-handed helical inorganic and hybrid organic-inorganic nanotubes is well developed, approaches to the formation of single-handed organopolymeric nanotubes are limited. Here, left-handed helical m-phenylenediamine-formaldehyde resin and 3-aminophenol-formaldehyde resin nanotubes were prepared by using N-palmitoyl glucosamine that can self-assemble into left-handed twisted nanoribbons in a mixture of methanol and water. In the reaction mixture, the helical pitch of the nanoribbons decreased with increasing reaction time. The resin nanotubes were obtained after removing the N-palmitoyl glucosamine template, and circular dichroism spectroscopy indicated that the organopolymeric nanotubes had optical activity. Carbonaceous nanotubes were then prepared by carbonization of the 3-aminophenol-formaldehyde resin nanotubes. © 2017 Wiley Periodicals, Inc.

  13. [The comparison of characteristics of smooth pursuit in left-handed and right-handed persons].

    Science.gov (United States)

    Bozhkova, V P; Surovicheva, N S; Nikolaev, D P

    2010-01-01

    The estimation of the smooth pursuit efficiency in healthy young adults by method based on stroboscopic stimulation is given. The influence of manual function asymmetry on smooth pursuit was tested. Subjects were classified as left-handed or right-handed under a well known handedness questionnaire of Annett supplemented by Luria's tests. It was shown that the strong right-handed persons have a high quality of smooth pursuit of stimuli moving horizontally in rightward and leftward directions with the velocities 20 degrees/s and 25 degrees/s. Left-handed persons track similar stimuli, on the average, worse than the strong right-handed ones. It haven't been observed the influence of manual function asymmetry on the dependence of the smooth pursuit efficiency from the moving stimuli direction (left to right or right to left).

  14. Left-handed cardiac surgery: tips from set up to closure for trainees and their trainers.

    Science.gov (United States)

    Burdett, Clare; Dunning, Joel; Goodwin, Andrew; Theakston, Maureen; Kendall, Simon

    2016-09-01

    There are certain obstacles which left-handed surgeons can face when training but these are not necessary and often perpetuated by a lack of knowledge. Most have been encountered and overcome at some point but unless recorded and disseminated they will have to be resolved repeatedly by each trainee and their trainers. This article highlights difficulties that the left-hander may encounter in cardiac surgery and gives practical operative advice for both trainees and their trainers to help overcome them.

  15. A sinister plot? Facts, beliefs, and stereotypes about the left-handed personality.

    Science.gov (United States)

    Grimshaw, Gina M; Wilson, Marc S

    2013-01-01

    Is there a left-handed personality? Is there a left-handed stereotype? Although psychologists have enthusiastically compared left- and right-handers across myriad cognitive, behavioural, and neuropsychological domains, there has been very little empirical investigation of the relationship between handedness and personality. In Study 1 we assessed the Big 5 personality traits (extraversion, agreeableness, conscientiousness, emotionality, and openness to experience) in a sample of 662 young adults in New Zealand. Left- and right-handers did not differ on any factor. However, there was a curvilinear relationship between hand preference and extraversion; mixed-handers were more introverted than either left- or right-handers. This finding is consistent with other research indicating that degree may be of more psychological consequence than direction of handedness. In Study 2 we assessed beliefs and stereotypes about the left-handed personality. Both left- and right-handers shared the belief that left-handers are more introverted and open to experience than right-handers. This stereotype is not negative, and argues against the status of left-handers as a stigmatised group in modern Western culture.

  16. Incidence of intraoperative complications in cataract surgery performed by left-handed residents.

    Science.gov (United States)

    Kim, Jae Yong; Ali, Rasha; Cremers, Sandra Lora; Yun, Sung-Cheol; Henderson, Bonnie An

    2009-06-01

    To compare the incidence of intraoperative complications during cataract surgery performed by left-handed and right-handed residents and to find predictor variables for complications in resident-performed surgery. Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA. This retrospective chart review comprised cataract extractions performed by postgraduate fourth-year residents from July 1, 2001, to June 30, 2006. The incidence of posterior capsule tear and vitreous loss were the main outcomes. Univariate and multivariate logistic analyses incorporated the variables of patient age and sex; laterality of surgical eye; presence of diabetes mellitus, glaucoma, or age-related macular degeneration; history of vitrectomy; axial length; pseudoexfoliation; small pupils; white cataract; posterior polar cataract; handedness of resident; and academic quarter during which surgery occurred. Left-handed residents performed 170 (9.8%) of the 1730 surgeries. The incidence of posterior capsule tear and vitreous loss was significantly lower in surgeries performed by left-handed residents than in those performed by right-handed residents (P = .03 and Pleft-handed residents. Handedness and patient age were significant predictor variables for these complications.

  17. Reduced asymmetry in motor skill learning in left-handed compared to right-handed individuals.

    Science.gov (United States)

    McGrath, Robert L; Kantak, Shailesh S

    2016-02-01

    Hemispheric specialization for motor control influences how individuals perform and adapt to goal-directed movements. In contrast to adaptation, motor skill learning involves a process wherein one learns to synthesize novel movement capabilities in absence of perturbation such that they are performed with greater accuracy, consistency and efficiency. Here, we investigated manual asymmetry in acquisition and retention of a complex motor skill that requires speed and accuracy for optimal performance in right-handed and left-handed individuals. We further determined if degree of handedness influences motor skill learning. Ten right-handed (RH) and 10 left-handed (LH) adults practiced two distinct motor skills with their dominant or nondominant arms during separate sessions two-four weeks apart. Learning was quantified by changes in the speed-accuracy tradeoff function measured at baseline and one-day retention. Manual asymmetry was evident in the RH group but not the LH group. RH group demonstrated significantly greater skill improvement for their dominant-right hand than their nondominant-left hand. In contrast, for the LH group, both dominant and nondominant hands demonstrated comparable learning. Less strongly-LH individuals (lower EHI scores) exhibited more learning of their dominant hand. These results suggest that while hemispheric specialization influences motor skill learning, these effects may be influenced by handedness. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Large-scale modulation of left-handed passband in hybrid graphene/dielectric metasurface

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chuanbao; Bai, Yang; Qiao, Lijie [Key Laboratory of Environmental Fracture (Ministry of Education), University of Science and Technology Beijing (China); Zhou, Ji [State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, Beijing (China); Zhao, Qian [State Kay Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing (China)

    2017-08-15

    Large-scale modulation of the left-handed transmission with a high quality factor is greatly desired by high-performance optical devices, but the requirements are hard to be satisfied simultaneously. This paper presents a hybrid graphene/dielectric metasurface to realize a large transmission modulation for the left-handed passband at near-infrared frequencies via tuning the Fermi energy of graphene. By splitting the nanoblocks, i.e. introducing an additional symmetry breaking in the unit cell, the metasurface demonstrates an ultrahigh quality factor (Q ∼ 550) of Fano resonance with near-unity transmission and full 2π phase coverage due to the interference between Mie-type magnetic and electric resonances, which induces the negative refraction property. Besides, the split in the nanoblock greatly enhances the local field by increasing the critical coupling area, so the light-graphene interaction is promoted intensively. When the surface conductivity of graphene is electrically tuned, the hybrid graphene/dielectric metasurface exhibits a deep modulation of 85% for the left-handed passband, which is robust even for the highest loss of graphene. Moreover, the simple configuration remarkably reduces the fabrication requirements to facilitate the widespread applications. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Stopped light in a cylindrical waveguide with metamaterial

    Science.gov (United States)

    Xue, Yan Ling; Liu, Wei; Gu, Yiwei; School of Information Science; Tech Team

    2016-05-01

    The unique property of the novel type of left-handed material (LHM) is that it can support propagating wave with the group velocity and Poynting vector opposite to the wave vector. We propose a cylindrical waveguide with its core and cladding filled with right-handed material (RHM) and LHM, respectively, to investigate the sign-varying energy fluxes and their cancellation and to explore the new mechanism of stopping light. The normalized total energy flux is introduced as P =P1/+P2 |P1 | + |P2 | where Pi (i = 1,2) is the power confined in the waveguide core and cladding, respectively. There exist three situations: (1) P > 0 means P1 > |P2 | ; the propagation is in the forward mode; (2) P means P1 = |P2 | ; the energy fluxes in core and cladding fully cancels each other, the light-wave propagation comes to a complete standstill with the group velocity reducing to zero, and the energy is stored in the waveguide completely. For modes TE0n and TM0n we theoretically derive the expression of the normalized energy fluxes. As μ2 means the energy flux in the LHM cladding is negative, opposite to the phase velocity, the energy fluxes between the RHM core and LHM cladding may cancel each other. The total energy flux thus becomes zero. The numerical simulation shows that with appropriate electromagnetic frequency and waveguide core radius, the electromagnetic waves can reach a complete standstill. We consider two popularly used Drude models in the microwave and optical domains. This abstract is replacing DAMOP16-2016-000110.

  20. Bianisotropic metamaterial

    Science.gov (United States)

    El-Kady, Ihab F.; Reinke, Charles M.

    2017-07-18

    The topology of the elements of a metamaterial can be engineered from its desired electromagnetic constitutive tensor using an inverse group theory method. Therefore, given a desired electromagnetic response and a generic metamaterial elemental design, group theory is applied to predict the various ways that the element can be arranged in three dimensions to produce the desired functionality. An optimizer can then be applied to an electromagnetic modeling tool to fine tune the values of the electromagnetic properties of the resulting metamaterial topology.

  1. Confining model with composite left-handed and unconfined right-handed particles

    International Nuclear Information System (INIS)

    Bordi, F.; Gatto, R.; Dominici, D.; Florence Univ.

    1982-01-01

    We present a fermionic composite model in which left-handed quarks and leptons transform as bound states of three elementary fermions confined under a subcolor gauge group whereas their right-handed partners are unconfined singlets. All the elementary fermions, confined or unconfined, are classified into a single spinor representation. A mass-mechanism, originating from the breaking of the spinor representation, gives masses to the quarks and leptons, originally massless from the anomaly conditions. A natural mechanism arises for the neutrino mass matrix. (orig.)

  2. Left-handed and right-handed U(1) gauge symmetry

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi

    2018-01-01

    We propose a model with the left-handed and right-handed continuous Abelian gauge symmetry; U(1) L × U(1) R . Then three right-handed neutrinos are naturally required to achieve U(1) R anomaly cancellations, while several mirror fermions are also needed to do U(1) L anomaly cancellations. Then we formulate the model, and discuss its testability of the new gauge interactions at collider physics such as the large hadron collider (LHC) and the international linear collider (ILC). In particular, we can investigate chiral structure of the interactions by the analysis of forward-backward asymmetry based on polarized beam at the ILC.

  3. Pure associative tactile agnosia for the left hand: clinical and anatomo-functional correlations.

    Science.gov (United States)

    Veronelli, Laura; Ginex, Valeria; Dinacci, Daria; Cappa, Stefano F; Corbo, Massimo

    2014-09-01

    Associative tactile agnosia (TA) is defined as the inability to associate information about object sensory properties derived through tactile modality with previously acquired knowledge about object identity. The impairment is often described after a lesion involving the parietal cortex (Caselli, 1997; Platz, 1996). We report the case of SA, a right-handed 61-year-old man affected by first ever right hemispheric hemorrhagic stroke. The neurological examination was normal, excluding major somaesthetic and motor impairment; a brain magnetic resonance imaging (MRI) confirmed the presence of a right subacute hemorrhagic lesion limited to the post-central and supra-marginal gyri. A comprehensive neuropsychological evaluation detected a selective inability to name objects when handled with the left hand in the absence of other cognitive deficits. A series of experiments were conducted in order to assess each stage of tactile recognition processing using the same stimulus sets: materials, 3D geometrical shapes, real objects and letters. SA and seven matched controls underwent the same experimental tasks during four sessions in consecutive days. Tactile discrimination, recognition, pantomime, drawing after haptic exploration out of vision and tactile-visual matching abilities were assessed. In addition, we looked for the presence of a supra-modal impairment of spatial perception and of specific difficulties in programming exploratory movements during recognition. Tactile discrimination was intact for all the stimuli tested. In contrast, SA was able neither to recognize nor to pantomime real objects manipulated with the left hand out of vision, while he identified them with the right hand without hesitations. Tactile-visual matching was intact. Furthermore, SA was able to grossly reproduce the global shape in drawings but failed to extract details of objects after left-hand manipulation, and he could not identify objects after looking at his own drawings. This case

  4. Superpositions of Laguerre-Gaussian Beams in Strongly Nonlocal Left-handed Materials

    International Nuclear Information System (INIS)

    Zhong Weiping; Wang Liyang; Belic, Milivoj; Huang Tingwen

    2010-01-01

    We present beam solutions of the strongly nonlocal nonlinear Schroedinger equation in left-handed materials (LHMs). Different Laguerre-Gaussian (LG) necklace beams, such as symmetric and asymmetric single layer and multilayer necklace beams are created by the superposition of two single beams with different topological charges. Such superpositions are then propagated through LHMs, displaying linear diffraction. It is found that the superposition of two LG nm beams with opposite topological charges does not show rotational behavior and that there exists rotation for other topological charge combinations. Our theory predicts that the accessible solitons cannot exist in LHMs. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  5. Functional MRI evaluation of supplementary motor area language dominance in right- and left-handed subjects.

    Science.gov (United States)

    Dalacorte, Amauri; Portuguez, Mirna Wetters; Maurer das Neves, Carlos Magno; Anes, Maurício; Dacosta, Jaderson Costa

    2012-01-01

    Functional magnetic resonance imaging (fMRI) is a non-invasive brain imaging technique widely used in the evaluation of the brain function that provides images with high temporal and spatial resolution. Investigation of the supplementary motor area (SMA) function is critical in the pre-surgical evaluation of neurological patients, since marked individual differences and complex overlapping with adjacent cortical areas exist, and it is important to spare the SMA from lesions when adjacent cortical tissue is surgically removed. We used fMRI to assess the activity of SMA in six right-handed and six left-handed healthy volunteers when a task requiring silent repetition of a series of words was given. Brain activation areas in each of the subjects were localized according to the standard Talairach coordinate space, and the individual voxels for each map were compared after 3D sagittal images were created and SMA was delimited. Quantitative analysis of hemispheric and bilateral SMA activation was described as mean ± standard deviation of hot points/total points. The results show that the language task induced bilateral SMA activation. Left SMA activation was significantly higher than right SMA activation in both right-handed and left-handed subjects.

  6. The respiratory syncytial virus nucleoprotein-RNA complex forms a left-handed helical nucleocapsid.

    Science.gov (United States)

    Bakker, Saskia E; Duquerroy, Stéphane; Galloux, Marie; Loney, Colin; Conner, Edward; Eléouët, Jean-François; Rey, Félix A; Bhella, David

    2013-08-01

    Respiratory syncytial virus (RSV) is an important human pathogen. Its nucleocapsid (NC), which comprises the negative sense RNA viral genome coated by the viral nucleoprotein N, is a critical assembly that serves as template for both mRNA synthesis and genome replication. We have previously described the X-ray structure of an NC-like structure: a decameric ring formed of N-RNA that mimics one turn of the helical NC. In the absence of experimental data we had hypothesized that the NC helix would be right-handed, as the N-N contacts in the ring appeared to more easily adapt to that conformation. We now unambiguously show that the RSV NC is a left-handed helix. We further show that the contacts in the ring can be distorted to maintain key N-N-protein interactions in a left-handed helix, and discuss the implications of the resulting atomic model of the helical NC for viral replication and transcription.

  7. Method for determining the effective permeability and permittivity of metamaterial

    Science.gov (United States)

    Butko, L. N.; Anzulevich, A. P.; Buchelnikov, V. D.; Fediy, A. A.; Bychkov, I. V.

    2017-09-01

    A easy method is proposed to use for the numerical determination of the permeability and permittivity by modeling the distribution of electromagnetic fields in the samples by finite element method based on the numerical solution of the differential equation with corresponding boundary conditions. Well-known metamaterial consisting of rectilinear thin wires array forming a 2D square lattice within the non-conductive host media was theoretically investigated in this paper. In the second photonic transparency range the investigated structure demonstrates the properties of both the left-handed metamaterial and the photonic crystal allowing Bragg diffraction of electromagnetic waves.

  8. Left-handed skeletally mature baseball players have smaller humeral retroversion in the throwing arm than right-handed players.

    Science.gov (United States)

    Takenaga, Tetsuya; Goto, Hideyuki; Sugimoto, Katsumasa; Tsuchiya, Atsushi; Fukuyoshi, Masaki; Nakagawa, Hiroki; Nozaki, Masahiro; Takeuchi, Satoshi; Otsuka, Takanobu

    2017-12-01

    It is known that the humeral retroversion of baseball players is greater in the throwing arm than in the nonthrowing arm. An investigation measuring dry bone specimens also showed that the right humerus had greater retroversion than the left. Considering these facts, it was hypothesized that humeral retroversion would differ between right- and left-handed players. This study aimed to compare the bilateral humeral retroversion between right- and left-handed skeletally mature baseball players. We investigated 260 (196 right-handed and 64 left-handed) male baseball players who belonged to a college or amateur team. Bilateral humeral retroversion was assessed using an ultrasound-assisted technique (humeral torsion angle [HTA]) as described by previous studies. Analysis of covariance, adjusted for handedness and baseball position, assessed the effect of throwing arm dominance on HTA. In comparison of the throwing arm, HTA was significantly smaller in left-handed (left humerus) than in right-handed (right humerus) players (77° vs. 81°; P left-handed (right humerus) than in right-handed (left humerus) players (73° vs. 69°; P left-handed than in right-handed players (3° vs. 12°; P left-handed skeletally mature baseball players was significantly smaller in the throwing arm, greater in the nonthrowing arm, and smaller in side-to-side differences than that of right-handed players. These findings may be key to understanding some of the biomechanical differences between right- and left-handed baseball players. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  9. Hyperbolic Metamaterials

    OpenAIRE

    Smolyaninov, Igor I.

    2015-01-01

    Hyperbolic metamaterials were originally introduced to overcome the diffraction limit of optical imaging. Soon thereafter it was realized that hyperbolic metamaterials demonstrate a number of novel phenomena resulting from the broadband singular behavior of their density of photonic states. These novel phenomena and applications include super resolution imaging, new stealth technologies, enhanced quantum-electrodynamic effects, thermal hyperconductivity, superconductivity, and interesting gra...

  10. Noninvasive brain stimulation for treatment of right- and left-handed poststroke aphasics.

    Science.gov (United States)

    Heiss, Wolf-Dieter; Hartmann, Alexander; Rubi-Fessen, Ilona; Anglade, Carole; Kracht, Lutz; Kessler, Josef; Weiduschat, Nora; Rommel, Thomas; Thiel, Alexander

    2013-01-01

    Accumulating evidence from single case studies, small case series and randomized controlled trials seems to suggest that inhibitory noninvasive brain stimulation (NIBS) over the contralesional inferior frontal gyrus (IFG) of right-handers in conjunction with speech and language therapy (SLT) improves recovery from poststroke aphasia. Application of inhibitory NIBS to improve recovery in left-handed patients has not yet been reported. A total of 29 right-handed subacute poststroke aphasics were randomized to receive either 10 sessions of SLT following 20 min of inhibitory repetitive transcranial magnetic stimulation (rTMS) over the contralesional IFG or 10 sessions of SLT following sham stimulation; 2 left-handers were treated according to the same protocol with real rTMS. Language activation patterns were assessed with positron emission tomography prior to and after the treatment; 95% confidence intervals for changes in language performance scores and the activated brain volumes in both hemispheres were derived from TMS- and sham-treated right-handed patients and compared to the same parameters in left-handers. Right-handed patients treated with rTMS showed better recovery of language function in global aphasia test scores (t test, p left-handed patients also improved, with 1 patient within the confidence limits of TMS-treated right-handers (23 points, 15.9-28.9) and the other patient within the limits of sham-treated subjects (8 points, 2.8-14.5). Both patients exhibited only a very small interhemispheric shift, much less than expected in TMS-treated right-handers, and more or less consolidated initially active networks in both hemispheres. Inhibitory rTMS over the nondominant IFG appears to be a safe and effective treatment for right-handed poststroke aphasics. In the 2 cases of left-handed aphasics no deterioration of language performance was observed with this protocol. However, therapeutic efficiency is less obvious and seems to be more related to the

  11. MEMS-Reconfigurable Metamaterials and Antenna Applications

    Directory of Open Access Journals (Sweden)

    Tomislav Debogovic

    2014-01-01

    Full Text Available This paper reviews some of our contributions to reconfigurable metamaterials, where dynamic control is enabled by microelectromechanical systems (MEMS technology. First, we show reconfigurable composite right-/left-handed transmission lines (CRLH-TLs having state of the art phase velocity variation and loss, thereby enabling efficient reconfigurable phase shifters and leaky-wave antennas (LWA. Second, we present very low loss metasurface designs with reconfigurable reflection properties, applicable in reflectarrays and partially reflective surface (PRS antennas. All the presented devices have been fabricated and experimentally validated. They operate in X- and Ku-bands.

  12. Tree-shaped fractal meta-surface with left-handed characteristics for absorption application

    Science.gov (United States)

    Faruque, M. R. I.; Hasan, M. M.; Islam, M. T.

    2018-02-01

    A tri-band fractal meta-surface absorber composed of metallic branches of a tree connected with a straight metal strip has been presented in this paper for high absorption application. The proposed tree-shaped structure shows resonance in C-, X-, and Ku-bands and left-handed characteristics in 14.15 GHz. The dimension of the tree-shaped meta-surface single unit cell structure is 9 × 9 mm2 and the effective medium ratio is 5.50. In addition, the designed absorber structure shows absorption above 84%, whereas the absorber structure printed on epoxy resin fiber substrate material. The FIT-based CST-MWS has been utilized for the design, simulation, and analysis purposes. Fabrication is also done for the experimental validation.

  13. Heart rate variability differs between right- and left-handed individuals.

    Science.gov (United States)

    Yüksel, Ramazan; Arslan, Muzeyyen; Dane, Senol

    2014-06-01

    Previous studies reported reduced longevity in left-handers with the suggestion that it may be associated with different heart diseases. Therefore, differences in heart rate variability (HRV), an index of autonomic cardiac activity, were examined for right- and left-handed individuals. 120 healthy young university students (75 women, 45 men; M age = 20.4 yr., SD = 1.5) volunteered. Handedness was assessed with the Edinburgh Handedness Inventory and HRV was measured via electrocardiography. The results suggest that the left-handers' HRV was significantly different from that of right-handers on several parameters. The atypical cerebral organization of left-handers may be related to an imbalanced autonomic system that results in higher frequencies of heart irregularities.

  14. Do Right- and Left-Handed Monkeys Differ on Cognitive Measures?

    Science.gov (United States)

    Hopkins, William D.; Washburn, David A.

    1994-01-01

    Twelve left- and 14 right-handed monkeys were compared on 6 measures of cognitive performance (2 maze-solving tasks, matching-to-sample, delayed matching-to-sample, delayed response using spatial cues, and delayed response using form cues). The dependent variable was trials-to-training criterion for each of the 6 tasks. Significant differences were found between left- and right-handed monkeys on the 2 versions of the delayed response task. Right-handed monkeys reached criterion significantly faster on the form cue version of the task, whereas left-handed monkeys reached criterion significantly faster on delayed response for spatial position (p less than .05). The results suggest that sensitive hand preference measures of laterality can reveal differences in cognitive performance, which in turn may reflect underlying laterality in functional organization of the nervous system.

  15. Kuznetsov-Ma waves train generation in a left-handed material

    Science.gov (United States)

    Atangana, Jacques; Giscard Onana Essama, Bedel; Biya-Motto, Frederick; Mokhtari, Bouchra; Cherkaoui Eddeqaqi, Noureddine; Crépin Kofane, Timoléon

    2015-03-01

    We analyze the behavior of an electromagnetic wave which propagates in a left-handed material. Second-order dispersion and cubic-quintic nonlinearities are considered. This behavior of an electromagnetic wave is modeled by a nonlinear Schrödinger equation which is solved by collective coordinates theory in order to characterize the light pulse intensity profile. More so, a specific frequency range has been outlined where electromagnetic wave behavior will be investigated. The perfect combination of second-order dispersion and cubic nonlinearity leads to a robust soliton. When the quintic nonlinearity comes into play, it provokes strong and long internal perturbations which lead to Benjamin-Feir instability. This phenomenon, also called modulational instability, induces appearance of a Kuznetsov-Ma waves train. We numerically verify the validity of Kuznetsov-Ma theory by presenting physical conditions which lead to Kuznetsov-Ma waves train generation. Thereafter, some properties of such waves train are also verified.

  16. Left-Handed Effect of Composite Rectangular SRRs and Its Application in Patch Antennae

    International Nuclear Information System (INIS)

    Ming, Huang; Yue-Qun, Zhou; Ting-Gen, Shen

    2010-01-01

    We concentrate on describing the important influence and physical law of the split resonant ring (SRR) based left-handed materials on patch antennae. The finite-difference time-domain method, together with the finite element method is used to study the characteristics of patch antennae based on composite rectangular SRRs. A novel composite rectangular SRR system is formed by assembling the conventional patch antennae and SRRs, it is found that electromagnetic wave resonance occurs near f = 3.15 GHz, the equivalent permittivity and permeability are both negative, and the electromagnetic wave's tunnel effect and evanescent waves' enhancing effect are formed, which can improve the localization extent of electromagnetic wave's energy apparently. Such effects can improve the antenna's radiation gain and its matching condition. The phenomenon indicates that such composite rectangular patch antennae are promising in wireless communications such as mobile phones, satellite communication and aviation. (fundamental areas of phenomenology(including applications))

  17. Variant lumbrical musculature of the left hand: Clinico-anatomic elucidation.

    Science.gov (United States)

    Singh, S; Loh, H K; Mehta, V

    2016-12-01

    Human hand is haughtily described in literature as 'revolution in evolution'. Lumbricals form an intricate part of its musculature playing a vital role in complex digital movements. By virtue of their origin from the volar aspect of palm and their insertion onto the dorsal aspect to the extensor digital expansion of the digits, lumbricals display complex actions flexing the metacarpophalangeal joint and extending the interphalangeal joints. Such manoeuvres of the digits are vital for skilful and precision movements. During routine dissection of the teaching program of undergraduate medical students, unusual origin and morphology of all the four lumbrical muscles in the left hand of a male cadaver was observed. Clinicians and hand surgeons should be aware of its variations while designing and dealing with hand surgeries. An attempt has been made to comprehend its clinical, embryological and phylogenetic aspects. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  18. Reversed Cherenkov-transition radiation in a waveguide partly filled with a left-handed medium

    Science.gov (United States)

    Alekhina, Tatiana Yu.; Tyukhtin, Andrey V.

    2018-04-01

    We analyze the electromagnetic field of a charged particle that moves uniformly in a circular waveguide and crosses a boundary between a vacuum area and an area filled with a left-handed medium exhibiting resonant frequency dispersion. The investigation of the waveguide mode components is performed analytically and numerically. The reversed Cherenkov radiation in the filled area of the waveguide and the reversed Cherenkov-transition radiation (RCTR) in the vacuum area are analyzed. The conditions for the excitation of RCTR are obtained. It is shown that the number of modes of RCTR is always finite; in particular, under certain conditions, the RCTR is composed of the first waveguide mode only. Plots of the typical fields of the excited waveguide mode are presented.

  19. Multiband Slot-Based Dual Composite Right/Left-Handed Transmission Line

    Directory of Open Access Journals (Sweden)

    E. Abdo-Sanchez

    2012-10-01

    Full Text Available A dual Composite Right-/Left-Handed Transmission Line (CRLH TL implementation that presents multiband behaviour is proposed in this contribution. The artificial TL is realized by loading a host microstrip line with alternate rectangular stubs and slots. The required series and shunt immittances are respectively provided by the slot and the stub. Due to the distributed nature of these immittances, the resultant phase response presents theoretically infinite RH and LH alternate bands, thus being appropriate for multiband applications. The design methodology is described with the help of a proposed TLs-based equivalent circuit and highlights the simplicity for balance condition. Full wave simulated results of the dispersion characteristics and frequency response of a unit-cell and a three-cells structure are presented.

  20. Reduced dream-recall frequency in left-handed adolescents: a replication.

    Science.gov (United States)

    Schredl, Michael; Beaton, Alan A; Henley-Einion, Josie; Blagrove, Mark

    2014-01-01

    The ability to recall a dream upon waking up in the morning has been linked to a broad variety of factors such as personality, creativity, sleep behaviour and cognitive function. There have been conflicting findings as to whether dream recall is related more to the right or to the left hemisphere, and conflicting findings regarding the relationship of dream-recall frequency to handedness. We have found previously that right- and mixed-handers report having more dreams than left-handers, a finding more pronounced among adolescents than adults. In the present sample of 3535 participants aged from 6 to 18 years, right-handedness and mixed/inconsistent handedness were associated with higher dream-recall frequency compared to that of left-handed persons, again especially in adolescents compared with children. Further research is required to uncover the reason for the lower frequency of dream recall by left-handers.

  1. Terahertz metamaterials

    Science.gov (United States)

    Peralta, Xomalin Guaiuli; Brener, Igal; O'Hara, John; Azad, Abul; Smirnova, Evgenya; Williams, John D.; Averitt, Richard D.

    2014-08-12

    Terahertz metamaterials comprise a periodic array of resonator elements disposed on a dielectric substrate or thin membrane, wherein the resonator elements have a structure that provides a tunable magnetic permeability or a tunable electric permittivity for incident electromagnetic radiation at a frequency greater than about 100 GHz and the periodic array has a lattice constant that is smaller than the wavelength of the incident electromagnetic radiation. Microfabricated metamaterials exhibit lower losses and can be assembled into three-dimensional structures that enable full coupling of incident electromagnetic terahertz radiation in two or three orthogonal directions. Furthermore, polarization sensitive and insensitive metamaterials at terahertz frequencies can enable new devices and applications.

  2. Auditory middle latency responses differ in right- and left-handed subjects: an evaluation through topographic brain mapping.

    Science.gov (United States)

    Mohebbi, Mehrnaz; Mahmoudian, Saeid; Alborzi, Marzieh Sharifian; Najafi-Koopaie, Mojtaba; Farahani, Ehsan Darestani; Farhadi, Mohammad

    2014-09-01

    To investigate the association of handedness with auditory middle latency responses (AMLRs) using topographic brain mapping by comparing amplitudes and latencies in frontocentral and hemispheric regions of interest (ROIs). The study included 44 healthy subjects with normal hearing (22 left handed and 22 right handed). AMLRs were recorded from 29 scalp electrodes in response to binaural 4-kHz tone bursts. Frontocentral ROI comparisons revealed that Pa and Pb amplitudes were significantly larger in the left-handed than the right-handed group. Topographic brain maps showed different distributions in AMLR components between the two groups. In hemispheric comparisons, Pa amplitude differed significantly across groups. A left-hemisphere emphasis of Pa was found in the right-handed group but not in the left-handed group. This study provides evidence that handedness is associated with AMLR components in frontocentral and hemispheric ROI. Handedness should be considered an essential factor in the clinical or experimental use of AMLRs.

  3. Foreign bodies of the ear and nose in children and its correlation with right or left handed children.

    Science.gov (United States)

    Peridis, Stamatios; Athanasopoulos, Ioannis; Salamoura, Maria; Parpounas, Konstantinos; Koudoumnakis, Emmanouel; Economides, John

    2009-02-01

    Foreign bodies (FB) of the ear and nose are common findings in the pediatric population. The objective of this project is to present our experience of cases presented to our department and to correlate the insertion of the FB in relation to the child's handedness. This project was carried out at the Department of Otorhinolaryngology Head and Neck Surgery of "Aghia Sophia" Children's Hospital (Athens, Greece), between December 2007 and August 2008. Data collected includes age and sex of the child, time elapsed between the insertion of the FB and its removal, type of FB, site of insertion, description of the child's handedness, conditions of removal and complications. 46 FB were removed from the nasal cavities. On the right nasal cavity, 29/31 (93.55%) children were right handed and 2/31 (6.45%) were left handed. On the left nasal cavity, 11/14 (78.57%) were right handed and 3/14 (21.43%) children were left handed. One right handed child had a FB in both nasal cavities. 44 FB were removed from the ear (external auditory canal: EAC), 30 (68.18%) from the right EAC and 14 (31.82%) from the left. On the right EAC, 28/30 (93.33%) children were right handed and 2/30 (6.67%) were left handed. Children with FB of the left EAC were 9/14 (64.29%) right handed and 5/14 (35.71%) left handed. Children insert FB into their nasal cavities randomly (P=0.308). As a result, there is no correlation with the child's handedness and right/left nasal cavities FB insertion. On the other hand, children do insert FB into their right/left EAC according whether they are right/left handed (P=0.014). Consequently, right handed children insert FB into their right EAC and left handed children into their left EAC.

  4. Left-handed polyproline-II helix revisited: proteins causing proteopathies.

    Science.gov (United States)

    Adzhubei, Alexei A; Anashkina, Anastasia A; Makarov, Alexander A

    2017-09-01

    Left-handed polyproline-II type helix is a regular conformation of polypeptide chain not only of fibrous, but also of folded and natively unfolded proteins and peptides. It is the only class of regular secondary structure substantially represented in non-fibrous proteins and peptides on a par with right-handed alpha-helix and beta-structure. In this study, we have shown that polyproline-II helix is abundant in several peptides and proteins involved in proteopathies, the amyloid-beta peptides, protein tau and prion protein. Polyproline-II helices form two interaction sites in the amyloid-beta peptides, which are pivotal for pathogenesis of Alzheimer's disease (AD). It also with high probability is the structure of the majority of tau phosphorylation sites, important for tau hyperphosphorylation and formation of neurofibrillary tangles, a hallmark of AD. Polyproline-II helices form large parts of the structure of the folded domain of prion protein. They can undergo conversion to beta-structure as a result of relatively small change of one torsional angle of polypeptide chain. We hypothesize that in prions and amyloids, in general polyproline-II helices can serve as structural elements of the normal structure as well as dormant nuclei of structure conversion, and thus play important role in structure changes leading to the formation of fibrils.

  5. Illusory movements induced by tendon vibration in right- and left-handed people.

    Science.gov (United States)

    Tidoni, Emmanuele; Fusco, Gabriele; Leonardis, Daniele; Frisoli, Antonio; Bergamasco, Massimo; Aglioti, Salvatore Maria

    2015-02-01

    Frequency-specific vibratory stimulation of peripheral tendons induces an illusion of limb movement that may be useful for restoring proprioceptive information in people with sensorimotor disability. This potential application may be limited by inter- and intra-subject variability in the susceptibility to such an illusion, which may depend on a variety of factors. To explore the influence of stimulation parameters and participants' handedness on the movement illusion, we vibrated the right and left tendon of the biceps brachii in a group of right- and left-handed people with five stimulation frequencies (from 40 to 120 Hz in step of 20 Hz). We found that all participants reported the expected illusion of elbow extension, especially after 40 and 60 Hz. Left-handers exhibited less variability in reporting the illusion compared to right-handers across the different stimulation frequencies. Moreover, the stimulation of the non-dominant arm elicited a more vivid illusion with faster onset relative to the stimulation of the dominant arm, an effect that was independent from participants' handedness. Overall, our data show that stimulation frequency, handedness and arm dominance influence the tendon vibration movement illusion. The results are discussed in reference to their relevance in linking motor awareness, improving current devices for motor ability recovery after brain or spinal damage and developing prosthetics and virtual embodiment systems.

  6. The Right Way to Teach Left-Handed Residents: Strategies for Training by Right Handers.

    Science.gov (United States)

    Prasad, Nikhil K; Kvasnovsky, Charlotte; Wise, Eric S; Kavic, Stephen M

    Left-handed (LH) residents remain underrepresented among surgical trainees, and there are few available data on how best to train them. The challenge is amplified when pairing a LH resident with a right-handed (RH) mentor. This report provides recommendations on how to improve the training of LH surgeons in a safe and effective manner. A comprehensive literature review was performed using different databases and search engines to identify all articles relevant to the training of LH residents. A total of 40 articles highlighted the challenges for LH surgical residents and RH mentors. Our recommendations are based on the following 4 themes: identifying inherent differences in left vs. RH residents, providing guidance to RH mentors training LH residents, adapting the RH environment to the LH surgeon, and maximizing safety during training. An organized approach needs to be taken in training the LH resident. Changes should be instituted at program-wide and national levels to ensure that the training experience of the sinistral surgical resident is optimized. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  7. Diastereomeric Right- and Left-Handed Helical Structures with Fourteen (R)-Chiral Centers.

    Science.gov (United States)

    Eto, Ryo; Oba, Makoto; Ueda, Atsushi; Uku, Tsubasa; Doi, Mitsunobu; Matsuo, Yosuke; Tanaka, Takashi; Demizu, Yosuke; Kurihara, Masaaki; Tanaka, Masakazu

    2017-12-22

    The relationship between chiral centers and the helical-screw control of their peptides has already been reported, but it has yet to be elucidated in detail. A chiral four-membered ring α,α-disubstituted α-amino acid with a (R,R)-butane-2,3-diol acetal moiety at the γ-position, but no α-chiral carbon, was synthesized. X-ray crystallographic analysis unambiguously revealed that its homo-chiral heptapeptide formed right-handed (P) and left-handed (M) 3 10 -helical structures at a ratio of 1:1. They appeared to be enantiomeric at the peptide backbone, but diastereomeric with fourteen (R)-configuration chiral centers. Conformational analyses of homopeptides in solution also indicated that diastereomeric (P) and (M) helices existed at approximately equal amounts, with a slight preference toward right-handedness, and they quickly interchanged at room temperature. The circumstances of chiral centers are important for the control of their helical-screw direction. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Practice Perspectives of Left-Handed Clinical Dental Students in India.

    Science.gov (United States)

    Kapoor, Shivam; Puranik, Manjunath P; Uma, S R

    2016-10-01

    Handedness becomes important for students during their training period. Limited literature is available regarding the same. The purpose of this study was to assess the dental practice perspectives and determine the hand preference and discomfort level among the Left-Handed (LH) clinical dental students. A 30-item survey tool was used to conduct a cross-sectional survey among four successive LH cohorts (third and final year undergraduates, dental interns and postgraduates) in all the dental colleges of Bengaluru, Karnataka, India, during the year 2014. A total of 84 students completed the survey, response rate being 100%. About one-third (37%) reported that their institution was not properly equipped to accommodate LH students. Majority felt that LH dentists were at a higher risk of developing musculoskeletal complications. Mouth mirror handling showed equal distribution for handedness as compared to the other dental activities, whereas discomfort levels were negligible ("without any difficulty"). Dental practice perspective scores significantly correlated with the difficulty levels (r=-0.333, pleft-handers had a right dental practice perspective and their responses indicate a need to address their issues empathetically.

  9. Accommodating Discontinuities in Dimeric Left-Handed Coiled Coils in ATP Synthase External Stalks

    Science.gov (United States)

    Wise, John G.; Vogel, Pia D.

    2009-01-01

    ATP synthases from coupling membranes are complex rotary motors that convert the energy of proton gradients across coupling membranes into the chemical potential of the β-γ anhydride bond of ATP. Proton movement within the ring of c subunits localized in the F0-sector drives γ and ɛ rotation within the F1α3β3 catalytic core where substrates are bound and products are released. An external stalk composed of homodimeric subunits b2 in Escherichia coli or heterodimeric bb′ in photosynthetic synthases connects F0 subunit a with F1 subunits δ and most likely α. The external stalk resists rotation, and is of interest both functionally and structurally. Hypotheses that the external stalk contributes to the overall efficiency of the reaction through elastic coupling of rotational substeps, and that stalks form staggered, right-handed coiled coils, are investigated here. We report on different structures that accommodate heptad discontinuities with either local or global underwinding. Analyses of the knob-and-hole packing of the E. coli b2 and Synechocystis bb′ stalks strongly support the possibility that these proteins can adopt conventional left-handed coiled coils. PMID:19348765

  10. Science in the Making: Right Hand, Left Hand. I: A BBC television programme broadcast in 1953.

    Science.gov (United States)

    McManus, I C; Rawles, Richard; Moore, James; Freegard, Matthew

    2010-01-01

    In August 1953, the BBC broadcast a television science programme entitled Science in the Making: Right Hand, Left Hand. The programme was broadcast live, being presented by Dr Jacob Bronowski in collaboration with Dr Kenneth Smith, and produced by George Noordhof. It not only presented a popular account of current ideas about right- and left-handedness, by using a group of celebrities (and a chimpanzee) in the studio, but also asked viewers to complete a brief questionnaire on handedness, which was printed in the Radio Times. Recently 6,336 of the returned questionnaires, which were said to have been analysed by Sir Cyril Burt and a colleague, were found in the archive of the Psychology Department of University College London. The present paper describes what we have discovered about the programme from various sources, including the producer and the son of Dr Kenneth Smith, and also presents basic descriptions of the postcards and the response to the programme. In two subsequent papers we will describe our analysis of the data from the postcards, which represents an unusual, large-scale survey of handedness in the mid-twentieth century.

  11. Science in the Making: Right Hand, Left Hand. II: The duck-rabbit figure.

    Science.gov (United States)

    McManus, I C; Freegard, Matthew; Moore, James; Rawles, Richard

    2010-01-01

    The BBC television programme Right Hand, Left Hand, broadcast in August 1953, showed a version of the duck-rabbit figure and asked viewers to say what they could see in the “puzzle picture”. Nearly 4,000 viewers described the image, and the answers to those questions have recently been found and analysed. The programme probably used the same version of the figure as appeared in Wittgenstein's Philosophical Investigations, which had been published a month or two previously. Although Dr Jacob Bronowski, the presenter of the programme, had suspected that left- and right-handers might differ in their perception of the figure, since they might scan it from different sides, in fact there is no relationship in the data between six measures of lateralisation and a propensity for seeing a duck or a rabbit. However the large data set does show separate effects of both age and sex on viewing the figure, female and older viewers being more likely to report seeing a rabbit (although a clear majority of viewers reported seeing a duck). There was also a very significant tendency for female viewers to use more typical descriptions of the duck, whereas males used a wider variety of types.

  12. On the Relation between Composite Right-/Left-Handed Transmission Lines and Chebyshev Filters

    Directory of Open Access Journals (Sweden)

    Changjun Liu

    2009-01-01

    Full Text Available Composite right-/left-handed (CRLH transmission lines have gained great interest in the microwave community. In practical applications, such CRLH sections realized by series and shunt resonators have a finite length. Starting from the observation that a high-order Chebyshev filter also exhibits a periodic central section of very similar structure, the relations between finite length CRHL transmission lines and Chebyshev filters are discussed in this paper. It is shown that a finite length CRLH transmission line in the balanced case is equivalent to the central part of a low-ripple high-order Chebyshev band-pass filter, and a dual-CRLH transmission line in the balanced case is equivalent to a low-ripple high-order Chebyshev band-stop filter. The nonperiodic end sections of a Chebyshev filter can be regarded as matching sections, thus leading to an even better amplitude and phase response. It is also shown that, equally to a CRHL transmission line, a Chebyshev filter exhibits negative phase velocity in part of its passband. As a consequence, an improved behavior of finite length CRLH transmission lines may be achieved adding matching sections based on filter theory; this is demonstrated by a simulation example.

  13. Broadband Butler Matrices with the Use of High-Pass LC Sections as Left-Handed Transmission Lines

    Directory of Open Access Journals (Sweden)

    K. Staszek

    2014-04-01

    Full Text Available An application of left-handed transmission line sections in Butler matrices has been investigated. It has been shown, for the first time, that the utilization of both left-handed and right-handed transmission lines allows for broadband differential phase shifters’ realization, required in the Butler matrices. A complete theoretical analysis is given, for Butler matrices incorporating ideal transmission lines of both right- and left handed types and expressions for the achievable bandwidth and differential phase deviation are derived. The presented idea has been verified by the design of a 4 x 4 Butler matrix operating in a frequency range of 2.5 – 3.5 GHz. As an artificial left-handed transmission line, an equivalent high-pass LC circuit realized in a quasi-lumped element technique, has been considered, and the resulting phase shift of such a circuit is given analytically. The obtained measurement results fully confirm the validity of the proposed idea of broadband Butler matrices’ realization.

  14. The laterality of stop and go processes of the motor response in left-handed and right-handed individuals.

    Science.gov (United States)

    Hiraoka, Koichi; Igawa, Kyudo; Kashiwagi, Mina; Nakahara, Chisato; Oshima, Yuki; Takakura, Yu

    2018-01-01

    The objective of the present study was to investigate whether the stop and go processes of the motor response are asymmetrical and whether the asymmetries are dependent on handedness and the response selection process that is engaged. Both right-handed and left-handed participants abducted either the left or right index finger in response to an imperative cue in the choice reaction time (choice RT) or the simple RT task. A stop cue was presented after the imperative cue with a probability of .25. When the stop cue was presented, the participants withheld the prepared response. On the choice RT task, left-handed participants had significantly shorter RT and stop signal reaction time (SSRT) with the left versus the right hand, whereas right-handers showed no difference between hands on either measure. In the simple RT task, the RT and SSRT were not significantly different between the groups or the response sides. These results indicate that both the stop and go processes of the prepared left-hand response are completed earlier than those of the right-hand response in left-handed individuals when the stimulus-response process involves a response selection process.

  15. What makes single-helical metamaterials generate "pure" circularly polarized light?

    Science.gov (United States)

    Wu, Lin; Yang, ZhenYu; Zhao, Ming; Zhang, Peng; Lu, ZeQing; Yu, Yang; Li, ShengXi; Yuan, XiuHua

    2012-01-16

    Circular polarizers with left-handed helical metamaterials can transmit right-handed circularly polarized (RCP) light with few losses. But a certain amount of left-handed circularly polarized (LCP) light will occur in the transmitted light, which is the noise of the circular polarizer. Therefore, we defined the ratio of the RCP light intensity to the LCP light intensity as the signal-to-noise (S/N) ratio. In our previous work, it's found that circular polarizers with multi-helical metamaterials have two orders higher S/N ratios than that of single-helical metamaterials. However, it has been a great challenge to fabricate such multi-helical structures with micron or sub-micron feature sizes. Is it possible for the single-helical metamaterials to obtain equally high S/N ratios as the multi-helical ones? To answer this question, we systematically investigated the influences of structure parameters of single-helical metamaterials on the S/N ratios using the finite-different time-domain (FDTD) method. It was found that the single-helical metamaterials can also reach about 30dB S/N ratios, which are equal to the multi-helical ones. Furthermore, we explained the phenomenon by the antenna theory and optimized the performances of the single-helical circular polarizers.

  16. Induction of RNAi Responses by Short Left-Handed Hairpin RNAi Triggers.

    Science.gov (United States)

    Hagopian, Jonathan C; Hamil, Alexander S; van den Berg, Arjen; Meade, Bryan R; Eguchi, Akiko; Palm-Apergi, Caroline; Dowdy, Steven F

    2017-10-01

    Small double-stranded, left-handed hairpin (LHP) RNAs containing a 5'-guide-loop-passenger-3' structure induce RNAi responses by a poorly understood mechanism. To explore LHPs, we synthesized fully 2'-modified LHP RNAs targeting multiple genes and found all to induce robust RNAi responses. Deletion of the loop and nucleotides at the 5'-end of the equivalent passenger strand resulted in a smaller LHP that still induced strong RNAi responses. Surprisingly, progressive deletion of up to 10 nucleotides from the 3'-end of the guide strand resulted in a 32mer LHP capable of inducing robust RNAi responses. However, further guide strand deletion inhibited LHP activity, thereby defining the minimal length guide targeting length to 13 nucleotides. To dissect LHP processing, we examined LHP species that coimmunoprecipitated with Argonaute 2 (Ago2), the catalytic core of RNA-induced silencing complex, and found that the Ago2-associated processed LHP species was of a length that correlated with Ago2 cleavage of the passenger strand. Placement of a blocking 2'-OMe blocking modification at the LHP predicted Ago2 cleavage site resulted in an intact LHP loaded into Ago2 and no RNAi response. Taken together, these data argue that in the absence of a substantial loop, this novel class of small LHP RNAs enters the RNAi pathway by a Dicer-independent mechanism that involves Ago2 cleavage and results in an extended guide strand. This work establishes LHPs as an alternative RNAi trigger that can be produced from a single synthesis for potential use as an RNAi therapeutic.

  17. Right- and left-handed three-helix proteins. I. Experimental and simulation analysis of differences in folding and structure.

    Science.gov (United States)

    Glyakina, Anna V; Pereyaslavets, Leonid B; Galzitskaya, Oxana V

    2013-09-01

    Despite the large number of publications on three-helix protein folding, there is no study devoted to the influence of handedness on the rate of three-helix protein folding. From the experimental studies, we make a conclusion that the left-handed three-helix proteins fold faster than the right-handed ones. What may explain this difference? An important question arising in this paper is whether the modeling of protein folding can catch the difference between the protein folding rates of proteins with similar structures but with different folding mechanisms. To answer this question, the folding of eight three-helix proteins (four right-handed and four left-handed), which are similar in size, was modeled using the Monte Carlo and dynamic programming methods. The studies allowed us to determine the orders of folding of the secondary-structure elements in these domains and amino acid residues which are important for the folding. The obtained data are in good correlation with each other and with the experimental data. Structural analysis of these proteins demonstrated that the left-handed domains have a lesser number of contacts per residue and a smaller radius of cross section than the right-handed domains. This may be one of the explanations of the observed fact. The same tendency is observed for the large dataset consisting of 332 three-helix proteins (238 right- and 94 left-handed). From our analysis, we found that the left-handed three-helix proteins have some less-dense packing that should result in faster folding for some proteins as compared to the case of right-handed proteins. Copyright © 2013 Wiley Periodicals, Inc.

  18. Spatial frequency maps of power flow in metamaterials and photonic crystals: Investigating backward-wave modes across the electromagnetic spectrum

    Science.gov (United States)

    Aghanejad, Iman; Markley, Loïc

    2017-11-01

    We present spatial frequency maps of power flow in metamaterials and photonic crystals in order to provide insights into their electromagnetic responses and further our understanding of backward power in periodic structures. Since 2001, many different structures across the electromagnetic spectrum have been presented in the literature as exhibiting an isotropic negative effective index. Although these structures all exhibit circular or spherical equifrequency contours that resemble those of left-handed media, here we show through k -space diagrams that the distribution of power in the spatial frequency domain can vary considerably across these structures. In particular, we show that backward power arises from high-order right-handed harmonics in photonic crystals, magnetodielectric crystals, and across the layers of coupled-plasmonic-waveguide metamaterials, while arising from left-handed harmonic pairs in split-ring resonator and wire composites, plasmonic crystals, and along the layers of coupled-plasmonic-waveguide metamaterials. We also show that the fishnet structure exhibits the same left-handed harmonic pairs as the latter group. These observations allow us to categorize different metamaterials according to their spatial spectral source of backward power and identify the mechanism behind negative refraction at a given interface. Finally, we discuss how k -space maps of power flow can be used to explain the high or low transmittance of power into different metamaterial or photonic crystal structures.

  19. Science in the Making: Right Hand, Left Hand. III: Estimating historical rates of left-handedness.

    Science.gov (United States)

    McManus, I C; Moore, James; Freegard, Matthew; Rawles, Richard

    2010-01-01

    The BBC television programme Right Hand, Left Hand, broadcast in August 1953, used a postal questionnaire to ask viewers about their handedness. Respondents were born between 1864 and 1948, and in principle therefore the study provides information on rates of left-handedness in those born in the nineteenth century, a group for which few data are otherwise available. A total of 6,549 responses were received, with an overall rate of left-handedness of 15.2%, which is substantially above that expected for a cohort born in the nineteenth and early twentieth centuries. Left-handers are likely to respond preferentially to surveys about handedness, and the extent of over-response can be estimated in modern control data obtained from a handedness website, from the 1953 BBC data, and from Crichton-Browne's 1907 survey, in which there was also a response bias. Response bias appears to have been growing, being relatively greater in the most modern studies. In the 1953 data there is also evidence that left-handers were more common among later rather than early responders, suggesting that left-handers may have been specifically recruited into the study, perhaps by other left-handers who had responded earlier. In the present study the estimated rate of bias was used to correct the nineteenth-century BBC data, which was then combined with other available data as a mixture of two constrained Weibull functions, to obtain an overall estimate of handedness rates in the nineteenth century. The best estimates are that left-handedness was at its nadir of about 3% for those born between about 1880 and 1900. Extrapolating backwards, the rate of left-handedness in the eighteenth century was probably about 10%, with the decline beginning in about 1780, and reaching around 7% in about 1830, although inevitably there are many uncertainties in those estimates. What does seem indisputable is that rates of left-handedness fell during most of the nineteenth century, only subsequently to rise in

  20. Cherenkov radiation by an electron bunch that moves in a vacuum above a left-handed material

    International Nuclear Information System (INIS)

    Averkov, Yu.O.; Yakovenko, V.M.

    2005-01-01

    Cherenkov radiation by a nonrelativistic electron bunch that moves above an interface of a vacuum-left-handed material has been investigated theoretically. The electron density of the bunch is described by a Gauss distribution. Cherenkov radiation for the frequency range where the refractive index is negative is shown to lead to simultaneous excitation of both bulk and surface electromagnetic waves over one and the same frequency range. In this case the wave vector magnitude in the plane of the interface of surface electromagnetic waves is larger than the corresponding wave vector magnitude of bulk electromagnetic waves. The energy flows in a left-handed material have been calculated. The spectral density and the radiation pattern have been investigated

  1. A compact very wideband amplifying filter based on RTD loaded composite right/left-handed transmission lines.

    Science.gov (United States)

    Abu-Marasa, Mahmoud O Mahmoud; El-Khozondar, Hala Jarallah

    2015-01-01

    The composite right/left-handed (CRLH) transmission line (TL) is presented as a general TL possessing both left-handed (LH) and right-handed (RH) natures. RH materials have both positive permittivity and positive permeability, and LH materials have both negative permittivity and negative permeability. This paper aims to design and analyze nonlinear CRLH-TL transmission line loaded with resonant tunneling diode (RTD). The main application of this design is a very wideband and compact filter that amplifies the travelling signal. We used OrCAD and ADS software to analyze the proposed circuit. CRLH-TL consists of a microstrip line which is loaded with complementary split-rings resonators (CSRRs), series gaps, and shunt inductor connected parallel to the RTD. The designed structure possess a wide band that ranges from 5 to 10.5 GHz and amplifies signal up to 50 %. The proposed design is of interest to microwave compact component designers.

  2. Effective Medium Ratio Obeying Wideband Left-Handed Miniaturized Meta-atoms for Multi-band Applications

    Science.gov (United States)

    Hossain, Mohammad Jakir; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

    2018-03-01

    In this paper, a miniaturized wideband left-handed (LH) meta-atom based on planar modified multiple hexagonal split ring resonators was designed, simulated, fabricated and tested that can maintain a left-handed property. An analysis and comparison of the different array structures were performed that obtained better effective medium ratio (EMR) and wideband (5.54 GHz) for multi band operations in the microwave regime. Finite-difference time-domain (FDTD) method based Computer Simulation Technology was implemented to design the meta-atom. The meta-atom showed multi-band response in conjunction with wideband and LH property over the certain frequency bands in the microwave spectra. The EMR was considerably improved compared to previously reported meta-atoms. The measured results showed good agreement with the simulated results. The dimensions, S-parameters and EMR parameters of the proposed miniaturized LH meta-atom are appropriate for L-, S-, C-, X-, and Ku-band applications.

  3. Right- and left-handed rules on the transverse spin angular momentum of a surface wave of photonic crystal.

    Science.gov (United States)

    Hu, Jinbing; Xia, Tongnan; Cai, Xiaoshu; Tian, Shengnan; Guo, Hanming; Zhuang, Songlin

    2017-07-01

    By investigating the surface wave of photonic crystal, we put forward two sets of rules: the right-handed screw rule, judging the transverse spin angular momentum (SAM) directions according to the propagation direction of the surface wave; and the left-handed rule, judging the excitation direction of the surface wave in accordance to the SAM direction of incident circularly polarized light and the relative position of the dipole-like scatterer with respect to the interface where the surface wave propagates. Both right- and left-handed rules apply to the interface consisting of opposite-sign-permittivity materials. With the help of these two sets of rules, it is convenient to judge the direction of the transverse SAM and the excited surface wave, which facilitate the application involving transverse SAM of the surface wave.

  4. Surgical skills acquisition among left-handed trainees-true inferiority or unfair assessment: a preliminary study.

    Science.gov (United States)

    Lee, Jason Y; Mucksavage, Phillip; McDougall, Elspeth M

    2013-01-01

    Studies involving the formal assessment of surgical skills have often reported inferior abilities among left-handed surgical trainees (LHT). Most surgical training curricula and assessment methods, however, are inherently geared toward right-handed trainees (RHT); potentially placing LHT at both a training and assessment disadvantage. We evaluated the effect of a hand dominance-based curriculum for acquisition of basic suturing and knot tying skills among medical students. After Institutional Review Board approval, first- and second-year medical students from the University of California, Irvine School of Medicine were recruited to participate in a basic suturing and knot tying skills course. Consenting students were randomized to either a left-handed curriculum or a right-handed curriculum consisting of (1) a 30-minute introductory video and (2) a 2-hour instructor-led, hands-on training session on basic suturing and knot tying. All instructional methods, instruments, and instructors were exclusively right-handed or left-handed for the right-handed curriculum or left-handed curriculum, respectively. Students were assessed on the performance of 2 suturing tasks, continuous running suturing and instrument knot tying, and performance assessments were conducted both immediately and 2 weeks posttraining. A total of 19 students completed the training course and both assessments (8 LHT, 11 RHT). Students randomized to a curriculum "concordant" with their hand dominance performed significantly better than those randomized to a "discordant" curriculum on both tasks (p hand dominance might have inferior acquisition of basic suturing and knot tying skills. Copyright © 2012 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  5. Mirrors in the PDB: left-handed α-turns guide design with D-amino acids

    Science.gov (United States)

    Annavarapu, Srinivas; Nanda, Vikas

    2009-01-01

    Background Incorporating variable amino acid stereochemistry in molecular design has the potential to improve existing protein stability and create new topologies inaccessible to homochiral molecules. The Protein Data Bank has been a reliable, rich source of information on molecular interactions and their role in protein stability and structure. D-amino acids rarely occur naturally, making it difficult to infer general rules for how they would be tolerated in proteins through an analysis of existing protein structures. However, protein elements containing short left-handed turns and helices turn out to contain useful information. Molecular mechanisms used in proteins to stabilize left-handed elements by L-amino acids are structurally enantiomeric to potential synthetic strategies for stabilizing right-handed elements with D-amino acids. Results Propensities for amino acids to occur in contiguous αL helices correlate with published thermodynamic scales for incorporation of D-amino acids into αR helices. Two backbone rules for terminating a left-handed helix are found: an αR conformation is disfavored at the amino terminus, and a βR conformation is disfavored at the carboxy terminus. Helix capping sidechain-backbone interactions are found which are unique to αL helices including an elevated propensity for L-Asn, and L-Thr at the amino terminus and L-Gln, L-Thr and L-Ser at the carboxy terminus. Conclusion By examining left-handed α-turns containing L-amino acids, new interaction motifs for incorporating D-amino acids into right-handed α-helices are identified. These will provide a basis for de novo design of novel heterochiral protein folds. PMID:19772623

  6. Mirrors in the PDB: left-handed alpha-turns guide design with D-amino acids.

    Science.gov (United States)

    Annavarapu, Srinivas; Nanda, Vikas

    2009-09-22

    Incorporating variable amino acid stereochemistry in molecular design has the potential to improve existing protein stability and create new topologies inaccessible to homochiral molecules. The Protein Data Bank has been a reliable, rich source of information on molecular interactions and their role in protein stability and structure. D-amino acids rarely occur naturally, making it difficult to infer general rules for how they would be tolerated in proteins through an analysis of existing protein structures. However, protein elements containing short left-handed turns and helices turn out to contain useful information. Molecular mechanisms used in proteins to stabilize left-handed elements by L-amino acids are structurally enantiomeric to potential synthetic strategies for stabilizing right-handed elements with D-amino acids. Propensities for amino acids to occur in contiguous alpha(L) helices correlate with published thermodynamic scales for incorporation of D-amino acids into alpha(R) helices. Two backbone rules for terminating a left-handed helix are found: an alpha(R) conformation is disfavored at the amino terminus, and a beta(R) conformation is disfavored at the carboxy terminus. Helix capping sidechain-backbone interactions are found which are unique to alpha(L) helices including an elevated propensity for L-Asn, and L-Thr at the amino terminus and L-Gln, L-Thr and L-Ser at the carboxy terminus. By examining left-handed alpha-turns containing L-amino acids, new interaction motifs for incorporating D-amino acids into right-handed alpha-helices are identified. These will provide a basis for de novo design of novel heterochiral protein folds.

  7. Sites That Can Produce Left-Handed Amino Acids in the Supernova Neutrino Amino Acid Processing Model

    OpenAIRE

    Boyd, Richard N.; Famiano, Michael A.; Onaka, Takashi; Kajino, Toshitaka

    2018-01-01

    The Supernova Neutrino Amino Acid Processing model, which uses electron anti-neutrinos and the magnetic field from a source object such as a supernova to selectively destroy one amino acid chirality, is studied for possible sites that would produce meteoroids having partially left-handed amino acids. Several sites appear to provide the requisite magnetic field intensities and electron anti-neutrino fluxes. These results have obvious implications for the origin of life on Earth.

  8. Mirrors in the PDB: left-handed α-turns guide design with D-amino acids

    Directory of Open Access Journals (Sweden)

    Nanda Vikas

    2009-09-01

    Full Text Available Abstract Background Incorporating variable amino acid stereochemistry in molecular design has the potential to improve existing protein stability and create new topologies inaccessible to homochiral molecules. The Protein Data Bank has been a reliable, rich source of information on molecular interactions and their role in protein stability and structure. D-amino acids rarely occur naturally, making it difficult to infer general rules for how they would be tolerated in proteins through an analysis of existing protein structures. However, protein elements containing short left-handed turns and helices turn out to contain useful information. Molecular mechanisms used in proteins to stabilize left-handed elements by L-amino acids are structurally enantiomeric to potential synthetic strategies for stabilizing right-handed elements with D-amino acids. Results Propensities for amino acids to occur in contiguous αL helices correlate with published thermodynamic scales for incorporation of D-amino acids into αR helices. Two backbone rules for terminating a left-handed helix are found: an αR conformation is disfavored at the amino terminus, and a βR conformation is disfavored at the carboxy terminus. Helix capping sidechain-backbone interactions are found which are unique to αL helices including an elevated propensity for L-Asn, and L-Thr at the amino terminus and L-Gln, L-Thr and L-Ser at the carboxy terminus. Conclusion By examining left-handed α-turns containing L-amino acids, new interaction motifs for incorporating D-amino acids into right-handed α-helices are identified. These will provide a basis for de novo design of novel heterochiral protein folds.

  9. Sites that Can Produce Left-handed Amino Acids in the Supernova Neutrino Amino Acid Processing Model

    Science.gov (United States)

    Boyd, Richard N.; Famiano, Michael A.; Onaka, Takashi; Kajino, Toshitaka

    2018-03-01

    The Supernova Neutrino Amino Acid Processing model, which uses electron anti-neutrinos and the magnetic field from a source object such as a supernova to selectively destroy one amino acid chirality, is studied for possible sites that would produce meteoroids with partially left-handed amino acids. Several sites appear to provide the requisite magnetic field intensities and electron anti-neutrino fluxes. These results have obvious implications for the origin of life on Earth.

  10. Allograph errors and impaired access to graphic motor codes in a case of unilateral agraphia of the dominant left hand.

    Science.gov (United States)

    Hanley, J R; Peters, S

    2001-06-01

    This paper describes the case of a unilateral agraphic patient (GG) who makes letter substitutions only when writing letters and words with his dominant left hand. Accuracy is significantly greater when he is writing with his right hand and when he is asked to spell words orally. GG also makes case errors when writing letters, and will sometimes write words in mixed case. However, these allograph errors occur regardless of which hand he is using to write. In terms of cognitive models of peripheral dysgraphia (e.g., Ellis, 1988), it appears that he has an allograph level impairment that affects writing with both hands, and a separate problem in accessing graphic motor patterns that disrupts writing with the left hand only. In previous studies of left-handed patients with unilateral agraphia (Zesiger & Mayer, 1992; Zesiger, Pegna, & Rilliet, 1994), it has been suggested that allographic knowledge used for writing with both hands is stored exclusively in the left hemisphere, but that graphic motor patterns are represented separately in each hemisphere. The pattern of performance demonstrated by GG strongly supports such a conclusion.

  11. Automated processes in tennis: do left-handed players benefit from the tactical preferences of their opponents?

    Science.gov (United States)

    Loffing, Florian; Hagemann, Norbert; Strauss, Bernd

    2010-02-01

    Previous research on laterality in sport suggests an over-representation of left-handers in interactive sports such as tennis and cricket. These findings potentially reflect left-handers' advantage over their right-handed competitors in those sports. Although considered crucial for successful performance, the tactical component of their superiority has yet to be analysed. Two studies were conducted to test for a side bias in tennis players' tactical preferences. In the first study, 108 right- and left-handed players of varying skill watched rallies on a computer screen and had to indicate where they would place the ball in the opposing half. The results showed the tactical preference of players to place more balls on a left-handed opponent's mostly stronger forehand side compared with when faced with a right-hander. In the second study, 54 professional tennis matches involving right- and left-handers were analysed with respect to ball placement frequencies on the opponent's backhand side. Significantly fewer balls were hit to the backhand side of a left-handed opponent, thus replicating the findings of Study 1 in on-court situations. Both studies indicate players' preference to place shots to their right irrespective of their opponent's handedness. Findings support the assumption that left-handers might enjoy a strategic advantage in tennis.

  12. On the advantage of being left-handed in volleyball: further evidence of the specificity of skilled visual perception.

    Science.gov (United States)

    Loffing, Florian; Schorer, Jörg; Hagemann, Norbert; Baker, Joseph

    2012-02-01

    High ball speeds and close distances between competitors require athletes in interactive sports to correctly anticipate an opponent's intentions in order to render appropriate reactions. Although it is considered crucial for successful performance, such skill appears impaired when athletes are confronted with a left-handed opponent, possibly because of athletes' reduced perceptual familiarity with rarely encountered left-handed actions. To test this negative perceptual frequency effect hypothesis, we invited 18 skilled and 18 novice volleyball players to predict shot directions of left- and right-handed attacks in a video-based visual anticipation task. In accordance with our predictions, and with recent reports on laterality differences in visual perception, the outcome of left-handed actions was significantly less accurately predicted than the outcome of right-handed attacks. In addition, this left-right bias was most distinct when predictions had to be based on preimpact (i.e., before hand-ball contact) kinematic cues, and skilled players were generally more affected by the opponents' handedness than were novices. The study's findings corroborate the assumption that skilled visual perception is attuned to more frequently encountered actions.

  13. Subunit b-Dimer of the Escherichia coli ATP Synthase Can Form Left-Handed Coiled-Coils

    Science.gov (United States)

    Wise, John G.; Vogel, Pia D.

    2008-01-01

    One remaining challenge to our understanding of the ATP synthase concerns the dimeric coiled-coil stator subunit b of bacterial synthases. The subunit b-dimer has been implicated in important protein interactions that appear necessary for energy conservation and that may be instrumental in energy conservation during rotary catalysis by the synthase. Understanding the stator structure and its interactions with the rest of the enzyme is crucial to the understanding of the overall catalytic mechanism. Controversy exists on whether subunit b adopts a classic left-handed or a presumed right-handed dimeric coiled-coil and whether or not staggered pairing between nonhomologous residues in the homodimer is required for intersubunit packing. In this study we generated molecular models of the Escherichia coli subunit b-dimer that were based on the well-established heptad-repeat packing exhibited by left-handed, dimeric coiled-coils by employing simulated annealing protocols with structural restraints collected from known structures. In addition, we attempted to create hypothetical right-handed coiled-coil models and left- and right-handed models with staggered packing in the coiled-coil domains. Our analyses suggest that the available structural and biochemical evidence for subunit b can be accommodated by classic left-handed, dimeric coiled-coil quaternary structures. PMID:18326648

  14. Transferability of different classical force fields for right and left handed α-helices constructed from enantiomeric amino acids.

    Science.gov (United States)

    Biswas, Santu; Sarkar, Sujit; Pandey, Prithvi Raj; Roy, Sudip

    2016-02-21

    Amino acids can form d and l enantiomers, of which the l enantiomer is abundant in nature. The naturally occurring l enantiomer has a greater preference for a right handed helical conformation, and the d enantiomer for a left handed helical conformation. The other conformations, that is, left handed helical conformations of the l enantiomers and right handed helical conformations of the d enantiomers, are not common. The energetic differences between left and right handed alpha helical peptide chains constructed from enantiomeric amino acids are investigated using quantum chemical calculations (using the M06/6-311g(d,p) level of theory). Further, the performances of commonly used biomolecular force fields (OPLS/AA, CHARMM27/CMAP and AMBER) to represent the different helical conformations (left and right handed) constructed from enantiomeric (D and L) amino acids are evaluated. 5- and 10-mer chains from d and l enantiomers of alanine, leucine, lysine, and glutamic acid, in right and left handed helical conformations, are considered in the study. Thus, in total, 32 α-helical polypeptides (4 amino acids × 4 conformations of 5-mer and 10-mer) are studied. Conclusions, with regards to the performance of the force fields, are derived keeping the quantum optimized geometry as the benchmark, and on the basis of phi and psi angle calculations, hydrogen bond analysis, and different long range helical order parameters.

  15. Right- and left-handed three-helix proteins. II. Similarity and differences in mechanical unfolding of proteins.

    Science.gov (United States)

    Glyakina, Anna V; Likhachev, Ilya V; Balabaev, Nikolay K; Galzitskaya, Oxana V

    2014-01-01

    Here, we study mechanical properties of eight 3-helix proteins (four right-handed and four left-handed ones), which are similar in size under stretching at a constant speed and at a constant force on the atomic level using molecular dynamics simulations. The analysis of 256 trajectories from molecular dynamics simulations with explicit water showed that the right-handed three-helix domains are more mechanically resistant than the left-handed domains. Such results are observed at different extension velocities studied (192 trajectories obtained at the following conditions: v = 0.1, 0.05, and 0.01 Å ps(-1) , T = 300 K) and under constant stretching force (64 trajectories, F = 800 pN, T = 300 K). We can explain this by the fact, at least in part, that the right-handed domains have a larger number of contacts per residue and the radius of cross section than the left-handed domains. Copyright © 2013 Wiley Periodicals, Inc.

  16. Numerical and experimental investigation of fishnet-based metamaterial in a X-band waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Sabah, C; Roskos, H G, E-mail: Sabah@Physik.uni-frankfurt.de [Physikalisches Institut, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany)

    2011-06-29

    In this paper, a fishnet-based metamaterial for the microwave X-band frequencies is introduced and investigated both numerically and experimentally. The main innovation introduced here is that the structure is composed of dielectric and metallic parts in such a way that there is no connection between the metallic part of the metamaterial and the waveguide. The homogeneous-effective-medium theory is employed for the characterization of the structure. A left-handed region is identified using the simulated and experimental results. The performance of the structure is described by a figure-of-merit calculation. The measured results are in good agreement with the simulated ones which show that the proposed metamaterial operates well like a fishnet metamaterial at around 10 GHz.

  17. Numerical and experimental investigation of fishnet-based metamaterial in a X-band waveguide

    International Nuclear Information System (INIS)

    Sabah, C; Roskos, H G

    2011-01-01

    In this paper, a fishnet-based metamaterial for the microwave X-band frequencies is introduced and investigated both numerically and experimentally. The main innovation introduced here is that the structure is composed of dielectric and metallic parts in such a way that there is no connection between the metallic part of the metamaterial and the waveguide. The homogeneous-effective-medium theory is employed for the characterization of the structure. A left-handed region is identified using the simulated and experimental results. The performance of the structure is described by a figure-of-merit calculation. The measured results are in good agreement with the simulated ones which show that the proposed metamaterial operates well like a fishnet metamaterial at around 10 GHz.

  18. Cisplatin GG-crosslinks within single-stranded DNA: origin of the preference for left-handed helicity.

    Science.gov (United States)

    Monnet, Jordan; Kozelka, Jiří

    2012-10-01

    Molecular dynamics (MD) simulations of the single-stranded DNA trinucleotide TG*G*, with the G* guanines crosslinked by the antitumor drug cisplatin, were performed with explicit representation of the water as solvent. The purpose of the simulations was to explain previous NMR observations indicating that in single-stranded cisplatin-DNA adducts, the crosslinked guanines adopt a left-handed helical orientation, whereas in duplexes, the orientation is right-handed. The analysis of the MD trajectory of TG*G* has ascribed a crucial role to hydrogen-bonding (direct or through-water) interactions of the 5'-oriented NH(3) ligand of platinum with acceptor groups at the 5'-side of the crosslink, namely the TpG* phosphate and the terminal 5'-OH group. These interactions bring about some strain into the trinucleotide which is slightly but significantly (1-1.5 kcal.mol(-1)) higher for the right-handed orientation than for the left-handed one. During the unconstrained, 3 ns long MD simulation, left-handed conformations were ~15 times more abundant than the right-handed ones. This sampling difference agrees roughly with the calculated energy difference in strain energy. Overall, these results show that the Pt-GG crosslink within single-stranded DNA is malleable and can access different conformations at a moderate energy cost. This malleability could be of importance in interactions between the platinated DNA and cellular proteins, in which the DNA is locally unwound. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Darwin's left hand. Analysis of chiroptical properties of unirradiated and irradiated L- and D-amino acids

    International Nuclear Information System (INIS)

    Durchschlag, H.; Seidl, C.; Tiefenbach, K.J.

    2011-01-01

    Complete text of publication follows. Although normal chemical reactions roughly produce equal mixtures of left-handed and right-handed types, life used some specialized machinery to produce only left-handed forms of amino acids. Origin of life theories must explain how nature could produce the proper mirrored building blocks. There appear, however, to be no established reasons why left-handed amino acids should be favoured in biological systems, and the possible emergence of chiral uniqueness in living processes is still an unresolved riddle. In a multitude of experiments, we have tested the sensitivity of all L- and D- amino acids against X-irradiation and UV light exposure, with special emphasis on any differences in degradation, (thermal) stability and ability to act as substrates. Among the techniques tested, the spectroscopic techniques (UV absorption, fluorescence, and in particular far-UV circular dichroism) turned out to be most effective, in addition to crystallisation experiments. In this context, a variety of experimental conditions (pH, gassing conditions etc.) were chosen. For analysing the data of aromatic and non-aromatic amino acids, respectively, appropriate precautions have to be taken. As a result of our investigations, indeed, several significant dissimilarities between different types of amino acids and different enantiomers were established. For example, among the aromatic representatives, L and D forms of tyrosines turned out to show a quite different behaviour, while among the non-aromatics, L and D enantiomers of asparagines and glutamines established distinctly different characteristics. Overall, under definite conditions, D-isomers tend to be more sensitive to radiation than their L-counterparts. If this experimentally observed radiosensitivity of L and D enantiomers is indeed the reason for amino acid homochirality and the 'handedness of life' has to be elucidated in future experiments on earth and in space.

  20. The thermal effect on the left-handedness of the mesoscopic composite right-Left handed transmission line

    Science.gov (United States)

    Wei, Xiao-Jing; Zhao, Shun-Cai; Guo, Hong-Wei

    2017-10-01

    Starting from the quantum fluctuation of current in the mesoscopic composite right-left handed transmission line (CRLH-TL) in the thermal Fock state, we investigate the left-handedness dependent of the frequencies, intensity and quantum fluctuations of the current field in the CRLH-TL under different thermal environment. The results show that the intensity and quantum fluctuations of current field in lower frequency bands affect the left-handedness distinctly under different thermal environment. The thermal effect on the left-handedness in the mesoscopic CRLH-TL deserves further experimental investigation in its miniaturization application.

  1. Clinical psychomotor skills among left and right handed medical students: are the left-handed medical students left out?

    Science.gov (United States)

    Alnassar, Sami; Alrashoudi, Aljoharah Nasser; Alaqeel, Mody; Alotaibi, Hala; Alkahel, Alanoud; Hajjar, Waseem; Al-Shaikh, Ghadeer; Alsaif, Abdulaziz; Haque, Shafiul; Meo, Sultan Ayoub

    2016-03-22

    There is a growing perception that the left handed (LH) medical students are facing difficulties while performing the clinical tasks that involve psychomotor skill, although the evidence is very limited and diverse. The present study aimed to evaluate the clinical psychomotor skills among Right-handed (RH) and left-handed (LH) medical students. For this study, 54 (27 left handed and 27 right handed) first year medical students were selected. They were trained for different clinical psychomotor skills including suturing, laparoscopy, intravenous cannulation and urinary catheterization under the supervision of certified instructors. All students were evaluated for psychomotor skills by different instructors. The comparative performance of the students was measured by using a global rating scale, each selected criteria was allotted 5-points score with the total score of 25. There were no significant differences in the performance of psychomotor skills among LH and RH medical students. The global rating score obtained by medical students in suturing techniques was: LH 15.89 ± 2.88, RH 16.15 ± 2.75 (p = 0.737), cannulation techniques LH 20.44 ± 2.81, RH 20.70 ± 2.56 (p = 0.725), urinary catheterization LH 4.33 ± 0.96 RH 4.11 ± 1.05 (p = 0.421). For laparoscopic skills total peg transfer time was shorter among LH medical students compared to RH medical students (LH 129.85 ± 80.87 s vs RH 135.52 ± 104.81 s) (p = 0.825). However, both RH and LH students completed their procedure within the stipulated time. Among LH and RH medical students no significant difference was observed in performing the common surgical psychomotor skills. Surgical skills for LH or RH might not be a result of innate dexterity but rather the academic environment in which they are trained and assessed. Early laterality-related mentoring in medical schools as well as during the clinical residency might reduce the inconveniences faced by the left-handed

  2. ILQINS hexapeptide, identified in lysozyme left-handed helical ribbons and nanotubes, forms right-handed helical ribbons and crystals.

    Science.gov (United States)

    Lara, Cecile; Reynolds, Nicholas P; Berryman, Joshua T; Xu, Anqiu; Zhang, Afang; Mezzenga, Raffaele

    2014-03-26

    Amyloid fibrils are implicated in over 20 neurodegenerative diseases. The mechanisms of fibril structuring and formation are not only of medical and biological importance but are also relevant for material science and nanotechnologies due to the unique structural and physical properties of amyloids. We previously found that hen egg white lysozyme, homologous to the disease-related human lysozyme, can form left-handed giant ribbons, closing into nanotubes. By using matrix-assisted laser desorption ionization mass spectrometry analysis, we here identify a key component of such structures: the ILQINS hexapeptide. By combining atomic force microscopy and circular dichorism, we find that this fragment, synthesized by solid-phase peptide synthesis, also forms fibrillar structures in water at pH 2. However, all fibrillar structures formed possess an unexpected right-handed twist, a rare chirality within the corpus of amyloid experimental observations. We confirm by small- and wide-angle X-ray scattering and molecular dynamics simulations that these fibrils are composed of conventional left-handed β-sheets, but that packing stresses between adjacent sheets create this twist of unusual handedness. We also show that the right-handed fibrils represent a metastable state toward β-sheet-based microcrystals formation.

  3. Reconfigurable/tunable dual band/dual mode ferrite composite right/left-handed CPW coupled-line coupler

    Science.gov (United States)

    Abdalla, M. A.; Hu, Z.

    2017-09-01

    This paper presents the design, modeling and experimental verification of a novel reconfigurable/tunable dual band/dual mode ferrite composite right/left handed CPW coupled-line coupler. The composite right/left handed configuration has been realized by loading coupled CPW transmission lines with series inter-digital capacitors and shunt segment inductors. The coupler performance has been verified using the equivalent circuit model, electromagnetic full wave simulations and experimental measurements. The coupler operates on dual mode in that it has dual bands of operation with two different propagation mechanisms. The first band has only a reciprocal backward coupling whereas the second band has only nonreciprocal through propagation. The non-reciprocity isolation in the second band is better than average of 15 dB. Compared to conventional single band single mode coupled line coupler of length = 0.25 λg, the proposed novel dual band dual mode coupler length is almost the same (0.265 λg) at 4.5 GHz. Furthermore, the dual mode/dual band coupler can have tunable functionality.

  4. Analysis of EEG signal by flicker-noise spectroscopy: identification of right-/left-hand movement imagination.

    Science.gov (United States)

    Broniec, A

    2016-12-01

    Flicker-noise spectroscopy (FNS) is a general phenomenological approach to analyzing dynamics of complex nonlinear systems by extracting information contained in chaotic signals. The main idea of FNS is to describe an information hidden in correlation links, which are present in the chaotic component of the signal, by a set of parameters. In the paper, FNS is used for the analysis of electroencephalography signal related to the hand movement imagination. The signal has been parametrized in accordance with the FNS method, and significant changes in the FNS parameters have been observed, at the time when the subject imagines the movement. For the right-hand movement imagination, abrupt changes (visible as a peak) of the parameters, calculated for the data recorded from the left hemisphere, appear at the time corresponding to the initial moment of the imagination. In contrary, for the left-hand movement imagination, the meaningful changes in the parameters are observed for the data recorded from the right hemisphere. As the motor cortex is activated mainly contralaterally to the hand, the analysis of the FNS parameters allows to distinguish between the imagination of the right- and left-hand movement. This opens its potential application in the brain-computer interface.

  5. Correction: Stereodivergent synthesis of right- and left-handed iminoxylitol heterodimers and monomers. Study of their impact on β-glucocerebrosidase activity.

    Science.gov (United States)

    Stauffert, Fabien; Serra-Vinardell, Jenny; Gómez-Grau, Marta; Michelakakis, Helen; Mavridou, Irene; Grinberg, Daniel; Vilageliu, Lluïsa; Casas, Josefina; Bodlenner, Anne; Delgado, Antonio; Compain, Philippe

    2017-09-26

    Correction for 'Stereodivergent synthesis of right- and left-handed iminoxylitol heterodimers and monomers. Study of their impact on β-glucocerebrosidase activity' by Fabien Stauffert et al., Org. Biomol. Chem., 2017, 15, 3681-3705.

  6. [Transposition errors during learning to reproduce a sequence by the right- and the left-hand movements: simulation of positional and movement coding].

    Science.gov (United States)

    Liakhovetskiĭ, V A; Bobrova, E V; Skopin, G N

    2012-01-01

    Transposition errors during the reproduction of a hand movement sequence make it possible to receive important information on the internal representation of this sequence in the motor working memory. Analysis of such errors showed that learning to reproduce sequences of the left-hand movements improves the system of positional coding (coding ofpositions), while learning of the right-hand movements improves the system of vector coding (coding of movements). Learning of the right-hand movements after the left-hand performance involved the system of positional coding "imposed" by the left hand. Learning of the left-hand movements after the right-hand performance activated the system of vector coding. Transposition errors during learning to reproduce movement sequences can be explained by neural network using either vector coding or both vector and positional coding.

  7. Isotropic optical metamaterials

    DEFF Research Database (Denmark)

    Lederer, Falk; Rockstuhl, C.; Menzel, C.

    2010-01-01

    Metamaterial imaging applications require optical isotropy. We show that highly symmetric unit cells do not necessarily exhibit this property. We prove that the dispersion relation can be tailored using a supercell metama-terial. Such metamaterial exhibits an isotropic negative index close to -1...

  8. Metamaterials: A Personal View

    Directory of Open Access Journals (Sweden)

    A. Sihvola

    2009-06-01

    Full Text Available This article discusses fundamental properties of metamaterials. Firstly, it is argued that the defining property of metamaterials is emergence and not that they should display properties not observable in nature. In addition, the regime where matter can be assigned effective properties will be quantified using concepts of metamaterialization period and number of generations.

  9. Resonance Frequency and Bandwidth of the Negative/Positive n Mode of a Composite Right-/Left-Handed Transmission Line

    Directory of Open Access Journals (Sweden)

    Seong-Jung Kim

    2018-01-01

    Full Text Available In this study, the analytic expression for the positive/negative nth-mode resonance frequency of an N unit cell composite right-/left-handed (CRLH transmission line is derived. To explain the resonance mechanism of the nth mode, especially for the negative mode, the current distribution of the N unit cell CRLH transmission line is investigated with a circuit simulation. Results show that both positive and negative nth resonance modes have n times current variations, but their phase difference is 180° as expected. Moreover, the positive nth resonance occurs at a high frequency, whereas the negative nth resonance transpires at a low frequency, thus indicating that the negative resonance mode can be utilized for a small resonator. The correlation between the slope of the dispersion curve and the bandwidth is also observed. In sum, the balanced condition of the CRLH transmission line provides a broader bandwidth than the unbalanced condition.

  10. Metamaterials beyond electromagnetism

    Science.gov (United States)

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment—all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, ‘space-coiling’ metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials (‘meta-liquids’), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

  11. Metamaterials beyond electromagnetism.

    Science.gov (United States)

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment-all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, 'space-coiling' metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials ('meta-liquids'), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

  12. Negative refractive index and acoustic superlens from multiple scattering in single negative metamaterials.

    Science.gov (United States)

    Kaina, Nadège; Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy

    2015-09-03

    Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves. One of the most interesting of these is the ability to achieve superlensing--that is, to focus or image beyond the diffraction limit. This originates from the left-handed behavior--the property of refracting waves negatively--that is typical of negative index metamaterials. Yet reaching this goal requires the design of 'double negative' metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks or specific particles presenting multiple overlapping resonances. Such a requirement limits the applicability of double negative metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic metamaterials. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the

  13. Optical isotropic negative index metamaterials

    DEFF Research Database (Denmark)

    Menzel, Christoph; Paul, Thomas; Rockstuhl, Carsten

    2010-01-01

    Towards isotropic metamaterials, we analyze isofrequency surfaces of the dispersion relation of high symmetry metamaterials and show that they are optically not isotropic. We achieve instead isotropic metamaterials that consist of carefully designed multiple layers....

  14. Tunable and Memory Metamaterials

    Science.gov (United States)

    2015-12-02

    AFRL-AFOSR-VA-TR-2015-0402 TUNABLE AND MEMORY METAMATERIALS Dimitri Basov UNIVERSITY OF CALIFORNIA SAN DIEGO Final Report 12/02/2015 DISTRIBUTION A...DATES COVERED (From - To) 15-08-2010 to 14-08-2015 4. TITLE AND SUBTITLE TUNABLE AND MEMORY METAMATERIALS 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550...common limitations of infrared metamaterials in order to achieve low electromagnetic losses and broad tunability of the electromagnetic response. One

  15. Memorization of Sequences of Movements of the Right or the Left Hand by Right- and Left-Handers: Vector Coding.

    Science.gov (United States)

    Bobrova, E V; Bogacheva, I N; Lyakhovetskii, V A; Fabinskaja, A A; Fomina, E V

    2017-01-01

    In order to test the hypothesis of hemisphere specialization for different types of information coding (the right hemisphere, for positional coding; the left one, for vector coding), we analyzed the errors of right and left-handers during a task involving the memorization of sequences of movements by the left or the right hand, which activates vector coding by changing the order of movements in memorized sequences. The task was first performed by the right or the left hand, then by the opposite hand. It was found that both'right- and left-handers use the information about the previous movements of the dominant hand, but not of the non-dom" inant one. After changing the hand, right-handers use the information about previous movements of the second hand, while left-handers do not. We compared our results with the data of previous experiments, in which positional coding was activated, and concluded that both right- and left-handers use vector coding for memorizing the sequences of their dominant hands and positional coding for memorizing the sequences of non-dominant hand. No similar patterns of errors were found between right- and left-handers after changing the hand, which suggests that in right- and left-handersthe skills are transferred in different ways depending on the type of coding.

  16. Unraveling mysteries of personal performance style; biomechanics of left-hand position changes (shifting) in violin performance.

    Science.gov (United States)

    Visentin, Peter; Li, Shiming; Tardif, Guillaume; Shan, Gongbing

    2015-01-01

    Instrumental music performance ranks among the most complex of learned human behaviors, requiring development of highly nuanced powers of sensory and neural discrimination, intricate motor skills, and adaptive abilities in a temporal activity. Teaching, learning and performing on the violin generally occur within musico-cultural parameters most often transmitted through aural traditions that include both verbal instruction and performance modeling. In most parts of the world, violin is taught in a manner virtually indistinguishable from that used 200 years ago. The current study uses methods from movement science to examine the "how" and "what" of left-hand position changes (shifting), a movement skill essential during violin performance. In doing so, it begins a discussion of artistic individualization in terms of anthropometry, the performer-instrument interface, and the strategic use of motor behaviors. Results based on 540 shifting samples, a case series of 6 professional-level violinists, showed that some elements of the skill were individualized in surprising ways while others were explainable by anthropometry, ergonomics and entrainment. Remarkably, results demonstrated each violinist to have developed an individualized pacing for shifts, a feature that should influence timing effects and prove foundational to aesthetic outcomes during performance. Such results underpin the potential for scientific methodologies to unravel mysteries of performance that are associated with a performer's personal artistic style.

  17. Unraveling mysteries of personal performance style; biomechanics of left-hand position changes (shifting in violin performance

    Directory of Open Access Journals (Sweden)

    Peter Visentin

    2015-10-01

    Full Text Available Instrumental music performance ranks among the most complex of learned human behaviors, requiring development of highly nuanced powers of sensory and neural discrimination, intricate motor skills, and adaptive abilities in a temporal activity. Teaching, learning and performing on the violin generally occur within musico-cultural parameters most often transmitted through aural traditions that include both verbal instruction and performance modeling. In most parts of the world, violin is taught in a manner virtually indistinguishable from that used 200 years ago. The current study uses methods from movement science to examine the “how” and “what” of left-hand position changes (shifting, a movement skill essential during violin performance. In doing so, it begins a discussion of artistic individualization in terms of anthropometry, the performer-instrument interface, and the strategic use of motor behaviors. Results based on 540 shifting samples, a case series of 6 professional-level violinists, showed that some elements of the skill were individualized in surprising ways while others were explainable by anthropometry, ergonomics and entrainment. Remarkably, results demonstrated each violinist to have developed an individualized pacing for shifts, a feature that should influence timing effects and prove foundational to aesthetic outcomes during performance. Such results underpin the potential for scientific methodologies to unravel mysteries of performance that are associated with a performer’s personal artistic style.

  18. A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications.

    Science.gov (United States)

    Islam, Md Moinul; Islam, Mohammad Tariqul; Samsuzzaman, Md; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah; Mansor, Mohd Fais

    2015-01-23

    A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR) and capacitance-loaded strip (CLS) unit cells is presented for Ultra wideband (UWB) microwave imaging applications. Four left-handed (LH) metamaterial (MTM) unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR) with a capacitance-loaded strip (CLS) to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm³, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4-12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.

  19. A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications

    Directory of Open Access Journals (Sweden)

    Md. Moinul Islam

    2015-01-01

    Full Text Available A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR and capacitance-loaded strip (CLS unit cells is presented for Ultra wideband (UWB microwave imaging applications. Four left-handed (LH metamaterial (MTM unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR with a capacitance-loaded strip (CLS to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm3, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4–12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.

  20. A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications

    Science.gov (United States)

    Islam, Md. Moinul; Islam, Mohammad Tariqul; Samsuzzaman, Md.; Faruque, Mohammad Rashed Iqbal; Misran, Norbahiah; Mansor, Mohd Fais

    2015-01-01

    A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR) and capacitance-loaded strip (CLS) unit cells is presented for Ultra wideband (UWB) microwave imaging applications. Four left-handed (LH) metamaterial (MTM) unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR) with a capacitance-loaded strip (CLS) to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm3, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4–12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications. PMID:28787945

  1. Origin of Both Right- and Left-Handed Helicities in a Supramolecular Gel with and without Ni2+at the Supramolecular Level.

    Science.gov (United States)

    Go, Misun; Choi, Heekyoung; Moon, Cheol Joo; Park, Jaehyeon; Choi, Yeonweon; Lee, Shim Sung; Choi, Myong Yong; Jung, Jong Hwa

    2018-01-02

    We demonstrate the different origins of helical directions in polymeric gels derived from a hydrazone reaction in the absence and presence of Ni 2+ . The right-handed helicity of polymeric gels without Ni 2+ originates from the enantiomeric d-form alanine moiety embedded in the building block. However, the right-handed helicity is inverted to a left-handed helicity upon the addition of Ni 2+ , indicating that added Ni 2+ greatly affects the conformation of the polymeric gel by overcoming the influence of the enantiomer embedded in the building block on the helicity at the supramolecular level. More interestingly, the ratio of the right-toleft-handed helical fibers varies with the concentration of Ni 2+ , which converts from 100% right-handed helical fiber to 90% left-handed helical fiber. In the presence of Ni 2+ , both right- and left-handed helical fibers coexist at the supramolecular level. Some fibers also exhibit both right- and left-handed helicities in a single fiber.

  2. The formation of right-handed and left-handed chiral nanopores within a single domain during amino acid self-assembly on Au(111).

    Science.gov (United States)

    Yang, Sena; Jeon, Aram; Driver, Russell W; Kim, Yeonwoo; Jeon, Eun Hee; Kim, Sehun; Lee, Hee-Seung; Lee, Hangil

    2016-05-25

    We report the formation of both right- and left-handed chiral nanopores within a single domain during the self-assembly of an amino acid derivative on an inert Au(111) surface using STM. DFT calculations employed to rationalize this unusual result identified that intermolecular interactions between chiral, windmill-shaped tetramers are crucial for self-assembly.

  3. Right-handed and left-handed G-quadruplexes have the same DNA sequence: distinct conformations induced by an organic small molecule and potassium.

    Science.gov (United States)

    Fu, Boshi; Huang, Jinguo; Chen, Yuqi; Wang, Yafen; Xue, Tianrui; Xu, GuoHua; Wang, Shaoru; Zhou, Xiang

    2016-08-21

    Herein, we report two distinct G-quadruplex conformations of the same G-rich oligonucleotide, regulated by a small molecule. This is the first report in which both right- and left-handed G-quadruplex conformations have been obtained from the same sequence. We discriminated these two distinct conformations and investigated their kinetics and thermodynamics.

  4. Vibrant times for mechanical metamaterials

    DEFF Research Database (Denmark)

    Christensen, Johan; Kadic, Muamer; Kraft, Oliver

    2015-01-01

    Metamaterials are man-made designer matter that obtains its unusual effective properties by structure rather than chemistry. Building upon the success of electromagnetic and acoustic metamaterials, researchers working on mechanical metamaterials strive at obtaining extraordinary or extreme...... mass density, negative modulus, pentamode, anisotropic mass density, Origami, nonlinear, bistable, and reprogrammable mechanical metamaterials....

  5. Motor unit activity in biceps brachii of left-handed humans during sustained contractions with two load types.

    Science.gov (United States)

    Gould, Jeffrey R; Cleland, Brice T; Mani, Diba; Amiridis, Ioannis G; Enoka, Roger M

    2016-09-01

    The purpose of the study was to compare the discharge characteristics of single motor units during sustained isometric contractions that required either force or position control in left-handed individuals. The target force for the two sustained contractions (24.9 ± 10.5% maximal force) was identical for each biceps brachii motor unit (n = 32) and set at 4.7 ± 2.0% of maximal voluntary contraction (MVC) force above its recruitment threshold (range: 0.5-41.2% MVC force). The contractions were not sustained to task failure, but the duration (range: 60-330 s) was identical for each motor unit and the decline in MVC force immediately after the sustained contractions was similar for the two tasks (force: 11.1% ± 13.7%; position: 11.6% ± 9.9%). Despite a greater increase in the rating of perceived exertion during the position task (task × time interaction, P < 0.006), the amplitude of the surface-recorded electromyogram for the agonist and antagonist muscles increased similarly during the two tasks. Nonetheless, mean discharge rate of the biceps brachii motor units declined more during the position task (task × time interaction, P < 0.01) and the variability in discharge times (coefficient of variation for interspike interval) increased only during the position task (task × time interaction, P < 0.008). When combined with the results of an identical study on right-handers (Mottram CJ, Jakobi JM, Semmler JG, Enoka RM. J Neurophysiol 93: 1381-1392, 2005), the findings indicate that handedness does not influence the adjustments in biceps brachii motor unit activity during sustained submaximal contractions requiring either force or position control. Copyright © 2016 the American Physiological Society.

  6. Right- and Left-Handed Helices, What is in between? Interconversion of Helical Structures of Alternating Pyridinedicarboxamide/m-(phenylazo)azobenzene Oligomers.

    Science.gov (United States)

    Tao, Peng; Parquette, Jon R; Hadad, Christopher M

    2012-12-11

    Some unnatural polymers/oligomers have been designed to adopt a well-defined, compact, three-dimensional folding capability. Azobenzene units are common linkages in these oligomer designs. Two alternating pyridinedicarboxamide/m-(phenylazo)azobenzene oligomers that can fold into both right- and left-handed helices were studied computationally in order to understand their dynamical properties. Helical structures were shown to be the global minima among the many different conformations generated from the Monte Carlo simulations, and extended conformations have higher potential energies than compact ones. To understand the interconversion process between right- and left-handed helices, replica-exchange molecular dynamic (REMD) simulations were performed on both oligomers, and with this method, both right- and left-handed helices were successfully sampled during the simulations. REMD trajectories revealed twisted conformations as intermediate structures in the interconversion pathway between the two helical forms of these azobenzene oligomers. This mechanism was observed in both oligomers in current study and occurred locally in the larger oligomer. This discovery indicates that the interconversion between helical structures with different handedness goes through a compact and partially folded structure instead of globally unfold and extended structure. This is also verified by the nudged elastic band (NEB) calculations. The temperature weighted histogram analysis method (T-WHAM) was applied on the REMD results to generate contour maps of the potential of mean force (PMF). Analysis showed that right- and left-handed helices are equally sampled in these REMD simulations. In large oligomers, both right- and left-handed helices can be adopted by different parts of the molecule simultaneously. The interconversion between two helical forms can occur in the middle of the helical structure and not necessarily at the termini of the oligomer.

  7. Thermal hyperbolic metamaterials.

    Science.gov (United States)

    Guo, Yu; Jacob, Zubin

    2013-06-17

    We explore the near-field radiative thermal energy transfer properties of hyperbolic metamaterials. The presence of unique electromagnetic states in a broad bandwidth leads to super-planckian thermal energy transfer between metamaterials separated by a nano-gap. We consider practical phonon-polaritonic metamaterials for thermal engineering in the mid-infrared range and show that the effect exists in spite of the losses, absorption and finite unit cell size. For thermophotovoltaic energy conversion applications requiring energy transfer in the near-infrared range we introduce high temperature hyperbolic metamaterials based on plasmonic materials with a high melting point. Our work paves the way for practical high temperature radiative thermal energy transfer applications of hyperbolic metamaterials.

  8. Rolled-Up Metamaterials

    Directory of Open Access Journals (Sweden)

    Stephan Schwaiger

    2012-01-01

    Full Text Available In this paper we review metamaterials fabricated from self-rolling strained metal-semiconductor layer systems. These systems relax their strain upon release from the substrate by rolling up into microtubes with a cross-section similar to a rolled-up carpet. We show that the walls of these microtubes represent three-dimensional optical metamaterials which so far could be used, for example, for the realization of broadband hyperlenses, fishnet metamaterials, or optically active three-dimensional metamaterials utilizing the unique possibility to stack optically active semiconductor heterostructures and metallic nanostructures. Furthermore, we discuss THz metamaterials based on arrays of rolled-up metal semiconductor microtubes and helices.

  9. Isotropic Single Negative Metamaterials

    Directory of Open Access Journals (Sweden)

    P. Protiva

    2008-09-01

    Full Text Available This paper presents the application of simple, and therefore cheap, planar resonators for building 3D isotropic metamaterials. These resonators are: a broadside-coupled split ring resonator with a magnetic response providing negative permeability; an electric dipole terminated by a loop inductor together with a double H-shaped resonator with an electric response providing negative permittivity. Two kinds of 3D isotropic single negative metamaterials are reported. The first material consists of unit cells in the form of a cube bearing on its faces six equal planar resonators with tetrahedral symmetry. In the second material, the planar resonators boxed into spherical plastic shells and randomly distributed in a hosting material compose a real 3D volumetric metamaterial with an isotropic response. In both cases the metamaterial shows negative permittivity or permeability, according to the type of resonators that are used. The experiments prove the isotropic behavior of the cells and of the metamaterial specimens.

  10. A Novel Metamaterial MIMO Antenna with High Isolation for WLAN Applications

    Directory of Open Access Journals (Sweden)

    Nguyen Khac Kiem

    2015-01-01

    Full Text Available A compact 2×2 metamaterial-MIMO antenna for WLAN applications is presented in this paper. The MIMO antenna is designed by placing side by side two single metamaterial antennas which are constructed based on the modified composite right/left-handed (CRLH model. By adding another left-handed inductor, the total left-handed inductor of the modified CRLH model is increased remarkably in comparison with that of conventional CRLH model. As a result, the proposed metamaterial antenna achieves 60% size reduction in comparison with the unloaded antenna. The MIMO antenna is electrically small (30 mm × 44 mm with an edge-to-edge separation between two antennas of 0.06λ0 at 2.4 GHz. In order to reduce the mutual coupling of the antenna, a defected ground structure (DGS is inserted to suppress the effect of surface current between elements of the proposed antenna. The final design of the MIMO antenna satisfies the return loss requirement of less than −10 dB in a bandwidth ranging from 2.38 GHz to 2.5 GHz, which entirely covers WLAN frequency band allocated from 2.4 GHz to 2.48 GHz. The antenna also shows a high isolation coefficient which is less than −35 dB over the operating frequency band. A good agreement between simulation and measurement is shown in this context.

  11. Metamaterials Application in Sensing

    Directory of Open Access Journals (Sweden)

    Hui Sun

    2012-02-01

    Full Text Available Metamaterials are artificial media structured on a size scale smaller than wavelength of external stimuli, and they can exhibit a strong localization and enhancement of fields, which may provide novel tools to significantly enhance the sensitivity and resolution of sensors, and open new degrees of freedom in sensing design aspect. This paper mainly presents the recent progress concerning metamaterials-based sensing, and detailedly reviews the principle, detecting process and sensitivity of three distinct types of sensors based on metamaterials, as well as their challenges and prospects. Moreover, the design guidelines for each sensor and its performance are compared and summarized.

  12. Combinatorial Mechanical Metamaterials

    Science.gov (United States)

    van Hecke, Martin

    The structure of most mechanical metamaterials is periodic so that their design space is that of the unit cell. Here we introduce a combinatorial strategy to create a vast number of distinct mechanical metamaterials, each with a unique spatial texture and response. These are aperiodic stackings of anisotropic building blocks, and their functionality rests on both the block design and their stacking configuration which is governed by a tiling problem. We realize such metamaterials by 3D printing, and show that they act as soft machines, capable of pattern recognition and pattern analysis.

  13. Passive THz metamaterials

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Malureanu, Radu; Zalkovskij, Maksim

    2012-01-01

    In this work we present our activities in the fabrication and characterization of passive THz metamaterials. We use two fabrication processes to develop metamaterials either as free-standing metallic membranes or patterned metallic multi-layers on the substrates to achieve different functionaliti....... Our interest lies in metamaterials for a broad spectrum of linear properties in operations with THz waves, such as linear and circular polarizers, absorbers and devices with enhanced transmittivity, single layer dichroic and chiral systems. All the three steps (modelling, fabrication...

  14. Metamaterials and wave control

    CERN Document Server

    Lheurette, Eric

    2013-01-01

    Since the concept was first proposed at the end of the 20th Century, metamaterials have been the subject of much research and discussion throughout the wave community. More than 10 years later, the number of related published articles is increasing significantly. Onthe one hand, this success can be attributed to dreams of new physical objects which are the consequences of the singular properties of metamaterials. Among them, we can consider the examples of perfect lensing and invisibility cloaking. On other hand,metamaterials also provide new tools for the design of well-known wave functions s

  15. Hemispheric prevalence during chewing in normal right-handed and left-handed subjects: a functional magnetic resonance imaging preliminary study.

    Science.gov (United States)

    Bracco, Pietro; Anastasi, Giuseppe; Piancino, Maria Grazia; Frongia, Gianluigi; Milardi, Demetrio; Favaloro, Angelo; Bramanti, Placido

    2010-04-01

    This study evaluated the activation of different cortical areas during nondeliberate chewing of soft and hard boluses in five right-handed and five left-handed subjects with normal occlusion, to determine different hemispheric prevalences. The study was conducted with a functional Magnetic Resonance Imaging (1.5 T Magnetom Vision - Siemens Medical, Germany) using a head coil. The results showed that the most frequently activated areas were Brodmann's areas four and six in the primary motor and premotor cortex, the insula and Broca's area and, overall, showed greater activity of the cortical mastication area (CMA) in the right hemisphere for right-handed and in the left hemisphere for left-handed subjects.

  16. [Influence of "prehistory" of sequential movements of the right and the left hand on reproduction: coding of positions, movements and sequence structure].

    Science.gov (United States)

    Bobrova, E V; Liakhovetskiĭ, V A; Borshchevskaia, E R

    2011-01-01

    The dependence of errors during reproduction of a sequence of hand movements without visual feedback on the previous right- and left-hand performance ("prehistory") and on positions in space of sequence elements (random or ordered by the explicit rule) was analyzed. It was shown that the preceding information about the ordered positions of the sequence elements was used during right-hand movements, whereas left-hand movements were performed with involvement of the information about the random sequence. The data testify to a central mechanism of the analysis of spatial structure of sequence elements. This mechanism activates movement coding specific for the left hemisphere (vector coding) in case of an ordered sequence structure and positional coding specific for the right hemisphere in case of a random sequence structure.

  17. Analytical solution for wave propagation through a graded index interface between a right-handed and a left-handed material.

    Science.gov (United States)

    Dalarsson, Mariana; Tassin, Philippe

    2009-04-13

    We have investigated the transmission and reflection properties of structures incorporating left-handed materials with graded index of refraction. We present an exact analytical solution to Helmholtz' equation for a graded index profile changing according to a hyperbolic tangent function along the propagation direction. We derive expressions for the field intensity along the graded index structure, and we show excellent agreement between the analytical solution and the corresponding results obtained by accurate numerical simulations. Our model straightforwardly allows for arbitrary spectral dispersion.

  18. Analytical solution for wave propagation through a graded index interface between a right-handed and a left-handed material

    OpenAIRE

    Dalarsson, Mariana; Tassin, Philippe

    2012-01-01

    We have investigated the transmission and reflection properties of structures incorporating left-handed materials with graded index of refraction. We present an exact analytical solution to Helmholtz' equation for a graded index profile changing according to a hyperbolic tangent function along the propagation direction. We derive expressions for the field intensity along the graded index structure, and we show excellent agreement between the analytical solution and the corresponding results o...

  19. Negative refraction index of the quantum lossy left-handed transmission lines affected by the displaced squeezed Fock state and dissipation

    Science.gov (United States)

    Zhao, Shun-Cai; Wei, Xiao-Jing; Wu, Qi-Xuan

    2017-05-01

    Quantum lossy left-handed transmission lines (LHTLs) are central to the miniaturized application in microwave band. This work discusses the NRI of the quantized lossy LHTLs in the presence of the resistance and the conductance in a displaced squeezed Fock state (DSFS). And the results show some novel specific quantum characteristics of NRI caused by the DSFS and dissipation, which may be significant for its miniaturized application in a suit of novel microwave devices.

  20. Recognition and one-pot extraction of right- and left-handed semiconducting single-walled carbon nanotube enantiomers using fluorene-binaphthol chiral copolymers.

    Science.gov (United States)

    Akazaki, Kojiro; Toshimitsu, Fumiyuki; Ozawa, Hiroaki; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2012-08-01

    Synthesized single-walled carbon nanotubes (SWNTs) are mixtures of right- and left-handed helicity and their separation is an essential topic in nanocarbon science. In this paper, we describe the separation of right- and left-handed semiconducting SWNTs from as-produced SWNTs. Our strategy for this goal is simple: we designed copolymers composed of polyfluorene and chiral bulky moieties because polyfluorenes with long alkyl-chains are known to dissolve only semiconducting SWNTs and chiral binaphthol is a so-called BINAP family that possesses a powerful enantiomer sorting capability. In this study, we synthesized 12 copolymers, (9,9-dioctylfluorene-2,7-diyl)x((R)- or (S)-2,2'-dimethoxy-1,1'-binaphthalen-6,6-diyl)y, where x and y are copolymer composition ratios. It was found that, by a simple one-pot sonication method, the copolymers are able to extract either right- or left-handed semiconducting SWNT enantiomers with (6,5)- and (7,5)-enriched chirality. The separated materials were confirmed by circular dichroism, vis-near IR and photoluminescence spectroscopies. Interestingly, the copolymer showed inversion of SWNT enantiomer recognition at higher contents of the chiral binaphthol moiety. Molecular mechanics simulations reveal a cooperative effect between the degree of chirality and copolymer conformation to be responsible for these distinct characteristics of the extractions. This is the first example describing the rational design and synthesis of novel compounds for the recognition and simple sorting of right- and left-handed semiconducting SWNTs with a specific chirality.

  1. Tendon and ligament fibrillar crimps give rise to left-handed helices of collagen fibrils in both planar and helical crimps.

    Science.gov (United States)

    Franchi, Marco; Ottani, Vittoria; Stagni, Rita; Ruggeri, Alessandro

    2010-03-01

    Collagen fibres in tendons and ligaments run straight but in some regions they show crimps which disappear or appear more flattened during the initial elongation of tissues. Each crimp is formed of collagen fibrils showing knots or fibrillar crimps at the crimp top angle. The present study analyzes by polarized light microscopy, scanning electron microscopy, transmission electron microscopy the 3D morphology of fibrillar crimp in tendons and ligaments of rat demonstrating that each fibril in the fibrillar region always twists leftwards changing the plane of running and sharply bends modifying the course on a new plane. The morphology of fibrillar crimp in stretched tendons fulfills the mechanical role of the fibrillar crimp acting as a particular knot/biological hinge in absorbing tension forces during fibril strengthening and recoiling collagen fibres when stretching is removed. The left-handed path of fibrils in the fibrillar crimp region gives rise to left-handed fibril helices observed both in isolated fibrils and sections of different tendons and ligaments (flexor digitorum profundus muscle tendon, Achilles tendon, tail tendon, patellar ligament and medial collateral ligament of the knee). The left-handed path of fibrils represents a new final suprafibrillar level of the alternating handedness which was previously described only from the molecular to the microfibrillar level. When the width of the twisting angle in the fibrillar crimp is nearly 180 degrees the fibrils appear as left-handed flattened helices forming crimped collagen fibres previously described as planar crimps. When fibrils twist with different subsequent rotational angles (left-helical course but, running in many different nonplanar planes, they form wider helical crimped fibres.

  2. [Case of callosal disconnection syndrome with a chief complaint of right-hand disability, despite presence of left-hand diagonistic dyspraxia].

    Science.gov (United States)

    Okamoto, Yoko; Saida, Hisako; Yamamoto, Toru

    2009-04-01

    e report the case of 48-year-old right-handed male patient with an infarction affecting most part of the body and the splenium of the left half of the corpus callosum. Neuropsychological examination revealed typical signs of callosal disconnection including left-sided apraxia, diagonistic dyspraxia, left-sided agraphia, left-hand tactile anomia, left hemialexia, and right-sided constructional disability. Moreover, he complained of impairment in activities involving the right hand disability and agraphia. He could not stop behaving with his right hand when he had a vague idea. For example, he involuntarily picked up a tea bottle with his right hand when he had a desire to drink, although the action was not appropriate to that occasion. The imitation and utilization behavior did not imply this case, because his right hand behaviors were not exaggerated in response to external stimuli, such as the gestures of the examiner or the subjects in front of the patient. Unexpectedly, he complained about impairment of the activity of his right hand and was unaware of left hand apraxia or diagonistic dyspraxia; this trend continued for 6 months, at the time of this writing. We argue that the patient may have been subconsciouly aware of the symptoms of his left hand but had not verbalized them.

  3. Blackbody metamaterial lasers

    KAUST Repository

    Liu, Changxu

    2015-01-01

    We investigate both theoretically and experimentally a new type of laser, which exploits a broadband light "condensation" process sustained by the stimulated amplification of an optical blackbody metamaterial. © 2014 Optical Society of America.

  4. Electrically driven optical metamaterials.

    Science.gov (United States)

    Le-Van, Quynh; Le Roux, Xavier; Aassime, Abdelhanin; Degiron, Aloyse

    2016-06-22

    The advent of metamaterials more than 15 years ago has offered extraordinary new ways of manipulating electromagnetic waves. Yet, progress in this field has been unequal across the electromagnetic spectrum, especially when it comes to finding applications for such artificial media. Optical metamaterials, in particular, are less compatible with active functionalities than their counterparts developed at lower frequencies. One crucial roadblock in the path to devices is the fact that active optical metamaterials are so far controlled by light rather than electricity, preventing them from being integrated in larger electronic systems. Here we introduce electroluminescent metamaterials based on metal nano-inclusions hybridized with colloidal quantum dots. We show that each of these miniature blocks can be individually tuned to exhibit independent optoelectronic properties (both in terms of electrical characteristics, polarization, colour and brightness), illustrate their capabilities by weaving complex light-emitting surfaces and finally discuss their potential for displays and sensors.

  5. Programmable mechanical metamaterials

    NARCIS (Netherlands)

    Florijn, H.C.B.

    2016-01-01

    We present a novel strategy to overcome this limitation and create programmable me chanical metamaterials, where the response of a single structure is determined and can be changed by the amount of lateral confinement.

  6. Superconductor terahertz metamaterial

    OpenAIRE

    Gu, Jianqiang; Singh, Ranjan; Tian, Zhen; Cao, Wei; Xing, Qirong; Han, Jiaguang; Zhang, Weili

    2010-01-01

    We characterize the behaviour of split ring resonators made up of high-transition temperature YBCO superconductor using terahertz time domain spectroscopy. The superconductor metamaterial shows sharp change in the transmission spectrum at the fundamental inductive-capacitive resonance and the dipole resonance as the temperature dips below the transition temperature. Our results reveal that the high performance of such a metamaterial is limited by material imperfections and defects such as cra...

  7. Resonant dielectric metamaterials

    Science.gov (United States)

    Loui, Hung; Carroll, James; Clem, Paul G; Sinclair, Michael B

    2014-12-02

    A resonant dielectric metamaterial comprises a first and a second set of dielectric scattering particles (e.g., spheres) having different permittivities arranged in a cubic array. The array can be an ordered or randomized array of particles. The resonant dielectric metamaterials are low-loss 3D isotropic materials with negative permittivity and permeability. Such isotropic double negative materials offer polarization and direction independent electromagnetic wave propagation.

  8. Mechanical meta-materials

    OpenAIRE

    Zadpoor, A.A.

    2016-01-01

    The emerging concept of mechanical meta-materials has received increasing attention during the last few years partially due to the advances in additive manufacturing techniques that have enabled fabricating materials with arbitrarily complex micro/nano-architectures. The rationally designed micro/nano-architecture of mechanical meta-materials gives rise to unprecedented or rare mechanical properties that could be exploited to create advanced materials with novel functionalities. This paper pr...

  9. Metamaterials critique and alternatives

    CERN Document Server

    Munk, Ben A

    2009-01-01

    A Convincing and Controversial Alternative Explanation of Metamaterials with a Negative Index of Refraction In a book that will generate both support and controversy, one of the world's foremost authorities on periodic structures addresses several of the current fashions in antenna design-most specifically, the popular subject of double negative metamaterials. Professor Munk provides a comprehensive theoretical electromagnetic investigation of the issues and concludes that many of the phenomena claimed by researchers may be impossible. While denying the existence of negative refractio

  10. Electroencephalographic (eeg coherence between visual and motor areas of the left and the right brain hemisphere while performing visuomotor task with the right and the left hand

    Directory of Open Access Journals (Sweden)

    Simon Brežan

    2007-09-01

    Full Text Available Background: Unilateral limb movements are based on the activation of contralateral primary motor cortex and the bilateral activation of premotor cortices. Performance of a visuomotor task requires a visuomotor integration between motor and visual cortical areas. The functional integration (»binding« of different brain areas, is probably mediated by the synchronous neuronal oscillatory activity, which can be determined by electroencephalographic (EEG coherence analysis. We introduced a new method of coherence analysis and compared coherence and power spectra in the left and right hemisphere for the right vs. left hand visuomotor task, hypothesizing that the increase in coherence and decrease in power spectra while performing the task would be greater in the contralateral hemisphere.Methods: We analyzed 6 healthy subjects and recorded their electroencephalogram during visuomotor task with the right or the left hand. For data analysis, a special Matlab computer programme was designed. The results were statistically analysed by a two-way analysis of variance, one-way analysis of variance and post-hoc t-tests with Bonferroni correction.Results: We demonstrated a significant increase in coherence (p < 0.05 for the visuomotor task compared to control tasks in alpha (8–13 Hz in beta 1 (13–20 Hz frequency bands between visual and motor electrodes. There were no significant differences in coherence nor power spectra depending on the hand used. The changes of coherence and power spectra between both hemispheres were symmetrical.Conclusions: In previous studies, a specific increase of coherence and decrease of power spectra for the visuomotor task was found, but we found no conclusive asymmetries when performing the task with right vs. left hand. This could be explained in a way that increases in coherence and decreases of power spectra reflect symmetrical activation and cooperation between more complex visual and motor brain areas.

  11. Simultaneous formation of right- and left-handed anti-parallel coiled-coil interfaces by a coil2 fragment of human lamin A.

    Science.gov (United States)

    Kapinos, Larisa E; Burkhard, Peter; Herrmann, Harald; Aebi, Ueli; Strelkov, Sergei V

    2011-04-22

    The elementary building block of all intermediate filaments (IFs) is a dimer featuring a central α-helical rod domain flanked by the N- and C-terminal end domains. In nuclear IF proteins (lamins), the rod domain consists of two coiled-coil segments, coil1 and coil2, that are connected by a short non-helical linker. Coil1 and the C-terminal part of coil2 contain the two highly conserved IF consensus motifs involved in the longitudinal assembly of dimers. The previously solved crystal structure of a lamin A fragment (residues 305-387) corresponding to the second half of coil2 has yielded a parallel left-handed coiled coil. Here, we present the crystal structure and solution properties of another human lamin A fragment (residues 328-398), which is largely overlapping with fragment 305-387 but harbors a short segment of the tail domain. Unexpectedly, no parallel coiled coil forms within the crystal. Instead, the α-helices are arranged such that two anti-parallel coiled-coil interfaces are formed. The most significant interface has a right-handed geometry, which is accounted for by a characteristic 15-residue repeat pattern that overlays with the canonical heptad repeat pattern. The second interface is a left-handed anti-parallel coiled coil based on the predicted heptad repeat pattern. In solution, the fragment reveals only a weak dimerization propensity. We speculate that the C-terminus of coil2 might unzip, thereby allowing for a right-handed coiled-coil interface to form between two laterally aligned dimers. Such an interface might co-exist with a heterotetrameric left-handed coiled-coil assembly, which is expected to be responsible for the longitudinal A(CN) contact. Copyright © 2011. Published by Elsevier Ltd.

  12. Left-handed helical preference in an achiral peptide chain is induced by an L-amino acid in an N-terminal type II β-turn.

    Science.gov (United States)

    De Poli, Matteo; De Zotti, Marta; Raftery, James; Aguilar, Juan A; Morris, Gareth A; Clayden, Jonathan

    2013-03-15

    Oligomers of the achiral amino acid Aib adopt helical conformations in which the screw-sense may be controlled by a single N-terminal residue. Using crystallographic and NMR techniques, we show that the left- or right-handed sense of helical induction arises from the nature of the β-turn at the N terminus: the tertiary amino acid L-Val induces a left-handed type II β-turn in both the solid state and in solution, while the corresponding quaternary amino acid L-α-methylvaline induces a right-handed type III β-turn.

  13. Reconfigurable nanomechanical photonic metamaterials.

    Science.gov (United States)

    Zheludev, Nikolay I; Plum, Eric

    2016-01-01

    The changing balance of forces at the nanoscale offers the opportunity to develop a new generation of spatially reconfigurable nanomembrane metamaterials in which electromagnetic Coulomb, Lorentz and Ampère forces, as well as thermal stimulation and optical signals, can be engaged to dynamically change their optical properties. Individual building blocks of such metamaterials, the metamolecules, and their arrays fabricated on elastic dielectric membranes can be reconfigured to achieve optical modulation at high frequencies, potentially reaching the gigahertz range. Mechanical and optical resonances enhance the magnitude of actuation and optical response within these nanostructures, which can be driven by electric signals of only a few volts or optical signals with power of only a few milliwatts. We envisage switchable, electro-optical, magneto-optical and nonlinear metamaterials that are compact and silicon-nanofabrication-technology compatible with functionalities surpassing those of natural media by orders of magnitude in some key design parameters.

  14. Amorphous Gyroscopic Topological Metamaterials

    Science.gov (United States)

    Mitchell, Noah P.; Nash, Lisa M.; Hexner, Daniel; Turner, Ari M.; Irvine, William T. M.

    Mechanical topological metamaterials display striking mechanical responses, such as unidirectional surface modes that are impervious to disorder. This behavior arises from the topology of their vibrational spectra. All examples of topological metamaterials to date are finely-tuned structures such as crystalline lattices or jammed packings. Here, we present robust recipes for building amorphous topological metamaterials with arbitrary underlying structure and no long-range order. Using interacting gyroscopes as a model system, we demonstrate through experiment, simulation, and theoretical methods that the local geometry and interactions are sufficient to generate topological mobility gaps, allowing for spatially-resolved, real-space calculations of the Chern number. The robustness of our approach enables the design and self-assembly of non-crystalline materials with protected, unidirectional waveguides on the micro and macro scale.

  15. From metamaterials to metadevices

    Science.gov (United States)

    Zheludev, Nikolay I.; Kivshar, Yuri S.

    2012-11-01

    Metamaterials, artificial electromagnetic media that are structured on the subwavelength scale, were initially suggested for the negative-index 'superlens'. Later metamaterials became a paradigm for engineering electromagnetic space and controlling propagation of waves: the field of transformation optics was born. The research agenda is now shifting towards achieving tunable, switchable, nonlinear and sensing functionalities. It is therefore timely to discuss the emerging field of metadevices where we define the devices as having unique and useful functionalities that are realized by structuring of functional matter on the subwavelength scale. In this Review we summarize research on photonic, terahertz and microwave electromagnetic metamaterials and metadevices with functionalities attained through the exploitation of phase-change media, semiconductors, graphene, carbon nanotubes and liquid crystals. The Review also encompasses microelectromechanical metadevices, metadevices engaging the nonlinear and quantum response of superconductors, electrostatic and optomechanical forces and nonlinear metadevices incorporating lumped nonlinear components.

  16. Active terahertz metamaterial devices

    Science.gov (United States)

    Chen, Houtong; Padilla, Willie John; Averitt, Richard Douglas; O'Hara, John F.; Lee, Mark

    2010-11-02

    Metamaterial structures are taught which provide for the modulation of terahertz frequency signals. Each element within an array of metamaterial (MM) elements comprises multiple loops and at least one gap. The MM elements may comprise resonators with conductive loops and insulated gaps, or the inverse in which insulated loops are present with conductive gaps; each providing useful transmissive control properties. The metamaterial elements are fabricated on a semiconducting substrate configured with a means of enhancing or depleting electrons from near the gaps of the MM elements. An on to off transmissivity ratio of about 0.5 is achieved with this approach. Embodiments are described in which the MM elements incorporated within a Quantum Cascade Laser (QCL) to provide surface emitting (SE) properties.

  17. Metamaterial electromagnetic wave absorbers.

    Science.gov (United States)

    Watts, Claire M; Liu, Xianliang; Padilla, Willie J

    2012-06-19

    The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Three-dimensional metamaterials

    Science.gov (United States)

    Burckel, David Bruce [Albuquerque, NM

    2012-06-12

    A fabrication method is capable of creating canonical metamaterial structures arrayed in a three-dimensional geometry. The method uses a membrane suspended over a cavity with predefined pattern as a directional evaporation mask. Metallic and/or dielectric material can be evaporated at high vacuum through the patterned membrane to deposit resonator structures on the interior walls of the cavity, thereby providing a unit cell of micron-scale dimension. The method can produce volumetric metamaterial structures comprising layers of such unit cells of resonator structures.

  19. Suicidal single gunshot injury to the head: differences in site of entrance wound and direction of the bullet path between right- and left-handed--an autopsy study.

    Science.gov (United States)

    Nikolić, Slobodan; Zivković, Vladimir; Babić, Dragan; Juković, Fehim

    2012-03-01

    The aim of this study was to determine the differences in the anatomical site of a gunshot entrance wound and the direction of the bullet path between right- and left-handed subjects who committed a suicide by a single gunshot injury to the head. The retrospective autopsy study was performed for a 10-year period, and it included selected cases of single suicidal gunshot head injury, committed by handguns. We considered only contact or near-contact wounds. The sample included 479 deceased, with average age 47.1 ± 19.1 years (range, 12-89 years): 432 males and 47 females, with 317 right-handed, 25 left-handed, and 137 subjects with unknown dominant hand. In our observed sample, most cases involved the right temple as the site of entrance gunshot wound (about 67%), followed by the mouth (16%), forehead (7%), left temple (6%), submental (2%), and parietal region (1%). The left temple, right temple, and forehead were the sites of the gunshot entrance wounds, which were the best predictors of the handedness of the deceased (Spearman ρ = 0.149, P = 0.006). Our study showed that the direction of the bullet intracranial path in cases of suicide was even a more potent predictor of the handedness of the deceased (Spearman ρ = 0.263, P = 0.000; Wald = 149.503, P = 0.000).

  20. Lighting up left-handed Z-DNA: photoluminescent carbon dots induce DNA B to Z transition and perform DNA logic operations.

    Science.gov (United States)

    Feng, Lingyan; Zhao, Andong; Ren, Jinsong; Qu, Xiaogang

    2013-09-01

    Left-handed Z-DNA has been identified as a transient structure occurred during transcription. DNA B-Z transition has attracted much attention because of not only Z-DNA biological importance but also their relation to disease and DNA nanotechnology. Recently, photoluminescent carbon dots, especially highly luminescent nitrogen-doped carbon dots, have attracted much attention on their applications to bioimaging and gene/drug delivery because of carbon dots with low toxicity, highly stable photoluminescence and controllable surface function. However, it is still unknown whether carbon dots can influence DNA conformation or structural transition, such as B-Z transition. Herein, based on our previous series work on DNA interactions with carbon nanotubes, we report the first example that photoluminescent carbon dots can induce right-handed B-DNA to left-handed Z-DNA under physiological salt conditions with sequence and conformation selectivity. Further studies indicate that carbon dots would bind to DNA major groove with GC preference. Inspired by carbon dots lighting up Z-DNA and DNA nanotechnology, several types of DNA logic gates have been designed and constructed based on fluorescence resonance energy transfer between photoluminescent carbon dots and DNA intercalators.

  1. Left-hand somatosensory stimulation combined with visual scanning training in rehabilitation for post-stroke hemineglect: a randomised, double-blind study.

    Science.gov (United States)

    Polanowska, Katarzyna; Seniów, Joanna; Paprot, Ewa; Leśniak, Marcin; Członkowska, Anna

    2009-06-01

    The aim of this randomised, double-blind study was to investigate the therapeutic effectiveness of left-hand electrical stimulation for patients with post-stroke left visuo-spatial neglect. This approach was hypothesised to enhance activation of the right hemisphere attention system and to improve visual exploration of extrapersonal space. Participants (n = 40) in the study were in a relatively early stage of recovery from their first right hemisphere stroke, and were randomly assigned to the experimental (E) or control (C) group. Group E received conventional visual scanning training combined with electrostimulation of the left hand, while Group C received scanning training with sham stimulation. Their visuo-spatial neglect was assessed twice, prior to the rehabilitation programme and on its completion, using cancellation tests and a letter-reading task. The effect of electrostimulation on hemineglect was assessed following a single administration and after a month-long rehabilitation programme. Although the immediate effect of stimulation was poor, after a month-long rehabilitation period we found significantly greater improvement in Group E patients than in Group C patients. Interestingly, the presence of hemisensory loss did not weaken the observed effect. Therefore, we claim that contralesional hand stimulation combined with visual scanning was a more effective treatment for hemineglect rehabilitation than scanning training alone.

  2. [A case of combined sensation disturbance and clumsiness of the left hand caused by an infarction localized to brodmann areas 1 and 2].

    Science.gov (United States)

    Kutoku, Yumiko; Hagiwara, Hiroki; Ichikawa, Yaeko; Takeda, Katsuhiko; Sunada, Yoshihide

    2007-04-01

    A 70-year-old woman was admitted to our hospital with a complaint of numbness and clumsiness of the left hand. On physical examination 23 days after the onset of cerebral infarction, she showed no apparent muscle weakness. Although her elementary somatosensory function was mostly intact with a minimal joint position sensation disturbance, she showed disturbances in tactile recognition, two-point discrimination, and weight perception. She also had difficulty in discrete finger movement of her left hand, especially when her eyes were closed. Brain MRI disclosed a small infarction localized to Brodmann areas 1 and 2 in the right postcentral gyrus. In the left median nerve short-latency somatosensory evoked potentials (s-SEPs), the N20 potential was normally evoked. This finding also indicated that the area 3b was preserved. The sensory symptoms observed in this patient were compatible with the hierarchical somatosensory processing model in the postcentral gyrus proposed by Iwamura et al, in which the elementary sensation recognized in area 3 is transferred to areas 1 and 2, and then processed to discriminative sensation. The disturbed discrete finger movement in this patient probably resulted from impaired tactile recognition which could be compensated for by visual information.

  3. Mechanical meta-materials

    NARCIS (Netherlands)

    Zadpoor, A.A.

    2016-01-01

    The emerging concept of mechanical meta-materials has received increasing attention during the last few years partially due to the advances in additive manufacturing techniques that have enabled fabricating materials with arbitrarily complex micro/nano-architectures. The rationally designed

  4. Aperiodic-metamaterial-based absorber

    Directory of Open Access Journals (Sweden)

    Quanlong Yang

    2017-09-01

    Full Text Available The periodic-metamaterial-based perfect absorber has been studied broadly. Conversely, if the unit cell in the metamaterial-based absorber is arranged aperiodically (aperiodic-metamaterial-based absorber, how does it perform? Inspired by this, here we present a systematic study of the aperiodic-metamaterial-based absorber. By investigating the response of metamaterial absorbers based on periodic, Fibonacci, Thue-Morse, and quasicrystal lattices, we found that aperiodic-metamaterial-based absorbers could display similar absorption behaviors as the periodic one in one hand. However, their absorption behaviors show different tendency depending on the thicknesses of the spacer. Further studies on the angle and polarization dependence of the absorption behavior are also presented.

  5. Perspective on resonances of metamaterials.

    Science.gov (United States)

    Min, Li; Huang, Lirong

    2015-07-27

    Electromagnetic resonance as the most important characteristic of metamaterials enables lots of exotic phenomena, such as invisible, negative refraction, man-made magnetism, etc. Conventional LC-resonance circuit model as the most authoritative and classic model is good at explaining and predicting the fundamental resonance wavelength of a metamaterial, while feels hard for high-order resonances, especially for resonance intensity (strength of resonance, determining on the performance and efficiency of metamaterial-based devices). In present work, via an easy-to-understand mass-spring model, we present a different and comprehensive insight for the resonance mechanism of metamaterials, through which both the resonance wavelengths (including the fundamental and high-order resonance wavelengths) and resonance intensities of metamaterials can be better understood. This developed theory has been well verified by different-material and different-structure resonators. This perspective will provide a broader space for exploring novel optical devices based on metamaterials (or metasurfaces).

  6. Quantum entanglement distillation with metamaterials.

    Science.gov (United States)

    al Farooqui, Md Abdullah; Breeland, Justin; Aslam, Muhammad I; Sadatgol, Mehdi; Özdemir, Şahin K; Tame, Mark; Yang, Lan; Güney, Durdu Ö

    2015-07-13

    We propose a scheme for the distillation of partially entangled two-photon Bell and three-photon W states using metamaterials. The distillation of partially entangled Bell states is achieved by using two metamaterials with polarization dependence, one of which is rotated by π/2 around the direction of propagation of the photons. On the other hand, the distillation of three-photon W states is achieved by using one polarization dependent metamaterial and two polarization independent metamaterials. Upon transmission of the photons of the partially entangled states through the metamaterials the entanglement of the states increases and they become distilled. This work opens up new directions in quantum optical state engineering by showing how metamaterials can be used to carry out a quantum information processing task.

  7. All-dielectric metamaterials.

    Science.gov (United States)

    Jahani, Saman; Jacob, Zubin

    2016-01-01

    The ideal material for nanophotonic applications will have a large refractive index at optical frequencies, respond to both the electric and magnetic fields of light, support large optical chirality and anisotropy, confine and guide light at the nanoscale, and be able to modify the phase and amplitude of incoming radiation in a fraction of a wavelength. Artificial electromagnetic media, or metamaterials, based on metallic or polar dielectric nanostructures can provide many of these properties by coupling light to free electrons (plasmons) or phonons (phonon polaritons), respectively, but at the inevitable cost of significant energy dissipation and reduced device efficiency. Recently, however, there has been a shift in the approach to nanophotonics. Low-loss electromagnetic responses covering all four quadrants of possible permittivities and permeabilities have been achieved using completely transparent and high-refractive-index dielectric building blocks. Moreover, an emerging class of all-dielectric metamaterials consisting of anisotropic crystals has been shown to support large refractive index contrast between orthogonal polarizations of light. These advances have revived the exciting prospect of integrating exotic electromagnetic effects in practical photonic devices, to achieve, for example, ultrathin and efficient optical elements, and realize the long-standing goal of subdiffraction confinement and guiding of light without metals. In this Review, we present a broad outline of the whole range of electromagnetic effects observed using all-dielectric metamaterials: high-refractive-index nanoresonators, metasurfaces, zero-index metamaterials and anisotropic metamaterials. Finally, we discuss current challenges and future goals for the field at the intersection with quantum, thermal and silicon photonics, as well as biomimetic metasurfaces.

  8. The left hand second to fourth digit ratio (2D:4D does not discriminate world-class female gymnasts from age matched sedentary girls.

    Directory of Open Access Journals (Sweden)

    Maarten W Peeters

    Full Text Available INTRODUCTION: The second to fourth-digit-ratio (2D:4D, a putative marker of prenatal androgen action and a sexually dimorphic trait, has been suggested to be related with sports performance, although results are not univocal. If this relation exists, it is most likely to be detected by comparing extreme groups on the continuum of sports performance. METHODS: In this study the 2D:4D ratio of world-class elite female artistic gymnasts (n = 129, competing at the 1987 Rotterdam World-Championships was compared to the 2D:4D ratio of sedentary age-matched sedentary girls (n = 129, alongside with other anthropometric characteristics including other sexually dimorphic traits such as an androgyny index (Bayer & Bayley and Heath-Carter somatotype components (endomorphy, mesomorphy, ectomorphy using AN(COVA. 2D:4D was measured on X-rays of the left hand. RESULTS: Left hand 2D:4D digit ratio in world class elite female gymnasts (0.921±0.020 did not differ significantly from 2D:4D in age-matched sedentary girls (0.924±0.018, either with or without inclusion of potentially confounding covariates such as skeletal age, height, weight, somatotype components or androgyny index. Height (161.9±6.4 cm vs 155.4±6.6 cm p0.01, somatotype components (4.0/3.0/2.9 vs 1.7/3.7/3.2 for endomorphy (p<0.01, mesomorphy (p<0.01 and ectomorphy (p<0.05 respectively all differed significantly between sedentary girls and elite gymnasts. As expressed by the androgyny index, gymnasts have, on average, broader shoulders relative to their hips, compared to the reference sample. Correlations between the 2D:4D ratio and chronological age, skeletal age, and the anthropometric characteristics are low and not significant. CONCLUSION: Although other anthropometric characteristics of sexual dimorphism were significantly different between the two samples, the present study cannot discriminate sedentary girls from world-class female gymnasts by means of the left hand 2D:4D ratio.

  9. Manipulating scattering features by metamaterials

    Directory of Open Access Journals (Sweden)

    Lu Cui

    2016-01-01

    Full Text Available We present a review on manipulations of electromagnetic scattering features by using metamaterials or metasurfaces. Several approaches in controlling the scattered fields of objects are presented, including invisibility cloaks and radar illusions based on transformation optics, carpet cloak using gradient metamaterials, dc cloaks, mantle cloaks based on scattering cancellation, “skin” cloaks using phase compensation, scattering controls with coding/programmable metasurfaces, and scattering reductions by multilayered structures. Finally, the future development of metamaterials on scattering manipulation is predicted.

  10. Doped Chiral Polymer Metamaterials (DCPM)

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this research is to develop lightweight, flexible, compact metamaterials with tunable resonance frequencies for effective optical and communication tools...

  11. Doped Chiral Polymer Metamaterials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Doped Chiral Polymer Metamaterials (DCPM) with tunable resonance frequencies have been developed by adding plasmonic inclusions into chiral polymers with variable...

  12. Chiroptical properties of anionic and cationic porphyrins and metalloporphyrins in complex with left-handed Z-DNA and right-handed B-DNA.

    Science.gov (United States)

    Choi, Jung Kyu; D'Urso, Alessandro; Balaz, Milan

    2013-10-01

    We report the chiroptical signature and binding interactions of cationic (meso-tetrakis(4-N-methylptridyl)porphyrin, 2HT4) and anionic (meso-tetrakis(4-sulfonatophenyl)porphyrin, 2HTPPS) porphyrins and their zinc(II) and nickel(II) derivatives (ZnT4, ZnTPPS, NiT4, and NiTPPS) with right-handed B-form and two forms of left-handed Z-form of alternating guanine-cytosine polydeoxynucleotide poly(dG-dC)2. NiTPPS is able to spectroscopically discriminate between spermine-induced Z-DNA and Co(III)-induced Z-DNA via new induced circular dichroism signal in the visible region of the electromagnetic spectrum. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Relative effectiveness of dominant versus non-dominant hand position for rescuer's side of approach during chest compressions between right-handed and left-handed novice rescuers.

    Science.gov (United States)

    You, Je Sung; Kim, Hoon; Park, Jung Soo; Baek, Kyung Min; Jang, Mun Sun; Lee, Hye Sun; Chung, Sung Phil; Kim, SeungWhan

    2015-03-01

    The major components affecting high quality cardiopulmonary resuscitation (CPR) have been defined as the ability of the rescuer, hand position, position of the rescuer and victim, depth and rate of chest compressions, and fatigue. Until now, there have been no studies on dominant versus non-dominant hand position and the rescuer's side of approach. This study was designed to evaluate the effectiveness of hand position and approach side on the quality of CPR between right-handed (RH) and left-handed (LH) novice rescuers. 44 health science university students with no previous experience of basic life support (BLS) volunteered for the study. We divided volunteers into two groups by handedness. Adult BLS was performed on a manikin for 2 min in each session. The sequences were randomly performed on the manikin's left side of approach (Lap) with the rescuer's left hand in contact with the sternum (Lst), Lap/Rst, Rap/Lst and Rap/Rst. We compared the quality of chest compressions between the RH and LH groups according to predetermined positions. A significant decrease in mean compression depth between the two groups was only observed when rescuers performed in the Rap/Lst scenario, regardless of hand dominance. The frequency of correct hand placement also significantly decreased in the Lap/Rst position for the LH group. The performance of novice rescuers during chest compressions is influenced by the position of the dominant hand and the rescuer's side of approach. In CPR training and real world situations, a novice rescuer, regardless of handedness, should consider hand positions for contacting the sternum identical to the side of approach after approaching from the nearest and most accessible side, for optimal CPR performance. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  14. The left hand second to fourth digit ratio (2D:4D is not related to any physical fitness component in adolescent girls.

    Directory of Open Access Journals (Sweden)

    Maarten W Peeters

    Full Text Available INTRODUCTION: The second to fourth-digit-ratio (2D:4D, a putative marker of prenatal androgen action and a sexually dimorphic trait, has been suggested to be related with fitness and sports performance, although results are not univocal. Most studies however focus on a single aspect of physical fitness or one sports discipline. METHODS: In this study the 2D:4D ratio of 178 adolescent girls (age 13.5-18 y was measured on X-rays of the left hand. The relation between 2D:4D digit ratio and multiple aspects of physical fitness (balance, speed of limb movement, flexibility, explosive strength, static strength, trunk strength, functional strength, running speed/agility, and endurance was studied by correlation analyses and stepwise multiple regression. For comparison the relation between these physical fitness components and a selected number of objectively measured anthropometric traits (stature, mass, BMI, somatotype components and the Bayer & Bailey androgyny index are presented alongside the results of 2D:4D digit ratio. RESULTS: Left hand 2D:4D digit ratio (0.925±0.019 was not significantly correlated with any of the physical fitness components nor any of the anthropometric variables included in the present study. 2D:4D did not enter the multiple stepwise regression for any of the physical fitness components in which other anthropometric traits explained between 9.2% (flexibility and 33.9% (static strength of variance. CONCLUSION: Unlike other anthropometric traits the 2D:4D digit ratio does not seem to be related to any physical fitness component in adolescent girls and therefore most likely should not be considered in talent detection programs for sporting ability in girls.

  15. A 3D chiral metal-organic framework based on left-handed helices containing 3-amino-1 H-1,2,4-triazole ligand

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bing, E-mail: bliu_1203@163.com [College of Chemistry and Chemical Engineering, Shaanxi University of Sciences and Technology, Xi’an, 710021 Shaanxi (China); Yang, Tian-Yi [The High School Affricated to Shaanxi Normal University, Xi’an, 710061 Shaanxi (China); Feng, Hui-Jun; Zhang, Zong-Hui [Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an, 710062 Shaanxi (China); Xu, Ling, E-mail: xuling@snnu.edu.cn [Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an, 710062 Shaanxi (China)

    2015-10-15

    A chiral metal-organic framework, [Cu(atr)(OH)]·0.5H{sub 2}O·0.5en (1) (Hatr=3-amino-1 H-1,2,4-triazole, en=ethylenediamine), was constructed via diffusion reaction of the achiral Hatr ligand and CuSO{sub 4} as starting materials. Compound 1 crystallizes in the chiral space group P3{sub 2}21 and features a porous metal-organic framework with 44.1% solvent-accessible volume fabricated by left-handed helices with a pitch height of l{sub p}=10.442 Å. Six helices gather around in a cycle forming a large honeycomb channel with a 6.58 Å inner diameter. Cu(II) center and atr{sup ‒} ligand regarded as 3-connected nodes, compound 1 can be simplified to a 3-c uninodal (4.12{sup 2}) (qtz-h) topological network. A gradual decreasing in the magnetic moment depending on temperature decreasing indicates an antiferromagnetic interaction in 1. The powder XRD confirms the bulk sample is a single crystal pure phase, and the thermogravimetric analysis shows the thermal stability of 1 is up to ca. 240 °C. - Highlights: • The present 3D chiral MOF is built from achiral Hatr ligand. • Six left-handed helices gather into a honeycomb channel in chiral sp P3{sub 2}21. • Compound 1 shows a 3-c uninodal (4.12{sup 2}) or qtz-h topological network. • Compound 1 indicates an antiferromagnetic interaction.

  16. Dispersion management with metamaterials

    Science.gov (United States)

    Tassin, Philippe; Koschny, Thomas; Soukoulis, Costas M.

    2017-03-07

    An apparatus, system, and method to counteract group velocity dispersion in fibers, or any other propagation of electromagnetic signals at any wavelength (microwave, terahertz, optical, etc.) in any other medium. A dispersion compensation step or device based on dispersion-engineered metamaterials is included and avoids the need of a long section of specialty fiber or the need for Bragg gratings (which have insertion loss).

  17. Light propagation in multilayer metamaterials

    NARCIS (Netherlands)

    Maas, R.C.

    2015-01-01

    Metamaterials are artificially constructed materials composed of sub-wavelength building blocks that are designed to interact with light in ways that cannot be achieved with natural materials. Over the last years, improvements in nanoscale fabrication and in metamaterial design have led to the

  18. Controlling sound with acoustic metamaterials

    DEFF Research Database (Denmark)

    Cummer, Steven A. ; Christensen, Johan; Alù, Andrea

    2016-01-01

    Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales....... The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. Active acoustic metamaterials use external control to create......-scale metamaterial structures and converting laboratory experiments into useful devices. In this Review, we outline the designs and properties of materials with unusual acoustic parameters (for example, negative refractive index), discuss examples of extreme manipulation of sound and, finally, provide an overview...

  19. Synthesis, structure, and electrochemistry and magnetic properties of a novel 1D homochiral MnIII(5-Brsalen) coordination polymer with left-handed helical character

    Science.gov (United States)

    Dong, Dapeng; Yu, Naisen; Zhao, Haiyan; Liu, Dedi; Liu, Jia; Li, Zhenghua; Liu, Dongping

    2016-01-01

    A novel homochiral manganese (III) Mn(5-Brsalen) coordination polymer with left-handed helical character by spontaneous resolution on crystallization by using Mn(5-Brsalen) and 4,4-bipyridine, [MnIII(5-Brsalen)(4,4-bipy)]·ClO4·CH3OH (1) (4,4-bipy = 4,4-bipyridine) has been synthesized and structurally characterized by X-ray single-crystal diffraction, elemental analysis and infrared spectroscopy. In compound 1, each manganese(III) anion is six-coordinate octahedral being bonded to four atoms of 5-Brsalen ligand in an equatorial plane and two nitrogen atoms from a 4,4-bipyridine ligand in axial positions. The structure of compound 1 can be described a supramolecular 2D-like structure which was formed by the intermolecular π-stacking interactions between the neighboring chains of the aromatic rings of 4,4-bipyridine and 5-Brsalen molecules. UV-vis absorption spectrum, electrochemistry and magnetic properties of the compound 1 have also been studied.

  20. Practice makes perfect, but only with the right hand: sensitivity to perceptual illusions with awkward grasps decreases with practice in the right but not the left hand.

    Science.gov (United States)

    Gonzalez, C L R; Ganel, T; Whitwell, R L; Morrissey, B; Goodale, M A

    2008-01-31

    It has been proposed that the visual mechanisms that control well-calibrated actions, such as picking up a small object with a precision grip, are neurally distinct from those that mediate our perception of the object. Thus, grip aperture in such situations has been shown to be remarkably insensitive to many size-contrast illusions. But most of us have practiced such movements hundreds, if not thousands of times. What about less familiar and unpracticed movements? Perhaps they would be less likely to be controlled by specialized visuomotor mechanisms and would therefore be more sensitive to size-contrast illusions. To test this idea, we asked right-handed subjects to pick up small objects using either a normal precision grasp (thumb and index finger) or an awkward grasp (thumb and ring finger), in the context of the Ponzo illusion. Even though this size-contrast illusion had no effect on the scaling of the precision grasp, it did have a significant effect on the scaling of the awkward grasp. Nevertheless, after three consecutive days of practice, even the awkward grasp became resistant to the illusion. In a follow-up experiment, we found that awkward grasps with the left hand (in right handers) did not benefit from practice and remained sensitive to the illusion. We conclude that the skilled target-directed movements are controlled by visual mechanisms that are quite distinct from those controlling unskilled movements, and that these specialized visuomotor mechanisms may be lateralized to the left hemisphere.

  1. Chiroptical properties, binding affinity, and photostability of a conjugated zinc porphyrin dimer complexed with left-handed Z-DNA and right-handed B-DNA.

    Science.gov (United States)

    Choi, Jung Kyu; Reed, Aisha; Balaz, Milan

    2014-01-14

    We have studied the UV-vis absorption and chiroptical properties, binding affinity and photostability of a conjugated positively charged butadiyne-linked Zn(ii) porphyrin dimer bound to DNA sequence poly(dG-dC)2. Right-handed B-DNA, spermine-induced Z-DNA and Co(iii)-induced Z-DNA have been explored. Resonance light scattering (RLS) spectra showed formation of porphyrin aggregates in the presence of all DNA forms with the largest aggregates formed with B-DNA. The porphyrin dimer gave rise to induced bisignate circular dichroism (CD) signals in the presence of the left-handed Z-DNA conformations. On the other hand, the dimer stayed nearly chiroptically silent when complexed with the B-form of poly(dG-dC)2. Our results indicated that the conjugated Zn(ii) porphyrin dimer can be used as a sensor for the chiroptical detection of Z-DNA in the visible (400-500 nm) and near-infrared region of the electromagnetic spectrum (700-800 nm). The helicity of DNA had little effect on the dimer binding affinities. The photostability of the porphyrin dimer complexed with any form of DNA was higher than that of the free molecule. The porphyrin dimer bound to Z-DNA exhibited slower photobleaching than the B-DNA dimer complex.

  2. 12/10-Helical β-Peptide with Dynamic Folding Propensity: Coexistence of Right- and Left-Handed Helices in an Enantiomeric Foldamer.

    Science.gov (United States)

    Shin, Seonho; Lee, Mihye; Guzei, Ilia A; Kang, Young Kee; Choi, Soo Hyuk

    2016-10-12

    We present the first examples of atomic-resolution crystal data for the β-peptide 12/10-helix from oligomers of cis-2-aminocyclohexane carboxylic acid (cis-ACHC) with alternating chirality. The local conformations of two enantiomeric cis-ACHC dimer units suggested that a chiral β-peptide may adopt both right-handed and left-handed helical conformations in solution. To probe the conformational behavior of 12/10-helical β-peptides, the two reference helices with a single handedness were synthesized with a more rigidified cis-ACHC derivative. Comparison with these reference helices at low temperature revealed that a chiral cis-ACHC oligomer with alternating chirality indeed displays 12/10-helical conformations with both handedness that equilibrate rapidly in solution. This is a very rare example of chiral oligomers with helix inversion ability. The 12/10-helical backbone should be a valuable addition to potential scaffolds for applications involving helices with dynamic folding propensity.

  3. Solvent-Directed Switch of a Left-Handed 10/12-Helix into a Right-Handed 12/10-Helix in Mixed β-Peptides.

    Science.gov (United States)

    Thodupunuri, Prashanth; Katukuri, Sirisha; Ramakrishna, Kallaganti V S; Sharma, Gangavaram V M; Kunwar, Ajit C; Sarma, Akella V S; Hofmann, Hans-Jörg

    2017-02-17

    Present study describes the synthesis and conformational analysis of β-peptides from C-linked carbo-β-amino acids [β-Caa (l) ] with a d-lyxo furanoside side chain and β-hGly in 1:1 alternation. NMR and CD investigations on peptides with an (S)-β-Caa (l) monomer at the N-terminus revealed a right-handed 10/12-mixed helix. An unprecedented solvent-directed "switch" both in helical pattern and handedness was observed when the sequence begins with a β-hGly residue instead of a (S)-β-Caa (l) constituent. NMR studies on these peptides in chloroform indicated a left-handed 10/12-helix, while the CD spectrum in methanol inferred a right-handed secondary structure. The NMR data for these peptides in CD 3 OH showed the presence of a right-handed 12/10-helix. NMR investigations in acetonitrile indicated the coexistence of both helix types. Quantum chemical studies predicted a small energy difference of 0.3 kcal/mol between the two helix types, which may explain the possibility of solvent influence. Examples for a solvent-directed switch of both the H-bonding pattern and the handedness of foldamer helices are rare so far. A comparable solvent effect was not found in the corresponding peptides with (R)-β-Caa (l) residues, where right-handed 12/10-helices are predominating.

  4. A New Definition of Fractional Derivatives Based on Truncated Left-Handed Grünwald-Letnikov Formula with 0<α<1 and Median Correction

    Directory of Open Access Journals (Sweden)

    Zhiwu Liao

    2014-01-01

    Full Text Available We propose a new definition of fractional derivatives based on truncated left-handed Grünwald-Letnikov formula with 0<α<1 and median correction. Analyzing the difficulties to choose the fractional orders and unsatisfied processing results in signal processing using fractional-order partial differential equations and related methods; we think that the nonzero values of the truncated fractional order derivatives in the smooth regions are major causes for these situations. In order to resolve the problem, the absolute values of truncated parts of the G-L formula are estimated by the median of signal values of the remainder parts, and then the truncated G-L formula is modified by replacing each of the original signal value to the differences of the signal value and the median. Since the sum of the coefficients of the G-L formula is zero, the median correction can reduce the truncated errors greatly to proximate G-L formula better. We also present some simulation results and experiments to support our theory analysis.

  5. Design of a broadband hexagonal-shaped zeroth-order resonance antenna with metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Dong Sik; Kim, Kang Wook; Choi, Hyun Chul [Kyungpook National University, Daegu (Korea, Republic of)

    2014-11-15

    A broadband hexagonal-shaped metamaterials (MTMs)-based zeroth-order resonant (ZOR) antenna was designed and fabricated. The hexagonal shape of a top patch on a mushroom structure makes not only direct-current paths between the two ends of the patch but also round-current paths along the outside of the patch, thereby widening the resonance frequency of the mushroom MTM antenna. According to the shape of the hexagon patch, the presented antenna achieved impedance bandwidth of 58.6% corresponding to ultra-wideband technology. The proposed ZOR antenna was modeled by utilizing a composite right- and left-handed (CRLH) transmission line and provided 4 to 9.3 dBi of the antenna gain with reduced size as compared to conventional microstrip antennas at Ku- to K-band frequencies.

  6. Mid-infrared tunable metamaterials

    Science.gov (United States)

    Brener, Igal; Miao, Xiaoyu; Shaner, Eric A; Passmore, Brandon Scott; Jun, Young Chul

    2015-04-28

    A mid-infrared tunable metamaterial comprises an array of resonators on a semiconductor substrate having a large dependence of dielectric function on carrier concentration and a semiconductor plasma resonance that lies below the operating range, such as indium antimonide. Voltage biasing of the substrate generates a resonance shift in the metamaterial response that is tunable over a broad operating range. The mid-infrared tunable metamaterials have the potential to become the building blocks of chip based active optical devices in mid-infrared ranges, which can be used for many applications, such as thermal imaging, remote sensing, and environmental monitoring.

  7. Mid-infrared tunable metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Brener, Igal; Miao, Xiaoyu; Shaner, Eric A.; Passmore, Brandon Scott

    2017-07-11

    A mid-infrared tunable metamaterial comprises an array of resonators on a semiconductor substrate having a large dependence of dielectric function on carrier concentration and a semiconductor plasma resonance that lies below the operating range, such as indium antimonide. Voltage biasing of the substrate generates a resonance shift in the metamaterial response that is tunable over a broad operating range. The mid-infrared tunable metamaterials have the potential to become the building blocks of chip based active optical devices in mid-infrared ranges, which can be used for many applications, such as thermal imaging, remote sensing, and environmental monitoring.

  8. Advanced fabrication of hyperbolic metamaterials

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Sukham, Johneph; Panah, Mohammad Esmail Aryaee

    2017-01-01

    Hyperbolic metamaterials can provide unprecedented properties in accommodation of high-k (high wave vector) waves and enhancement of the optical density of states. To reach such performance the metamaterials have to be fabricated with as small imperfections as possible. Here we report on our...... advances in two approaches in fabrication of optical metamaterials. We deposit ultrathin ultrasmooth gold layers with the assistance of organic material (APTMS) adhesion layer. The technology supports the stacking of such layers in a multiperiod construction with alumina spacers between gold films, which...

  9. Wire metamaterials: physics and applications.

    Science.gov (United States)

    Simovski, Constantin R; Belov, Pavel A; Atrashchenko, Alexander V; Kivshar, Yuri S

    2012-08-16

    The physics and applications of a broad class of artificial electromagnetic materials composed of lattices of aligned metal rods embedded in a dielectric matrix are reviewed. Such structures are here termed wire metamaterials. They appear in various settings and can operate from microwaves to THz and optical frequencies. An important group of these metamaterials is a wire medium possessing extreme optical anisotropy. The study of wire metamaterials has a long history, however, most of their important and useful properties have been revealed and understood only recently, especially in the THz and optical frequency ranges where the wire media correspond to the lattices of microwires and nanowires, respectively. Another group of wire metamaterials are arrays and lattices of nanorods of noble metals whose unusual properties are driven by plasmonic resonances. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Optical Metamaterials Fundamentals and Applications

    CERN Document Server

    Cai, Wenshan

    2010-01-01

    Metamaterials—artificially structured materials with engineered electromagnetic properties—have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities. In just a few years, the field of optical metamaterials has emerged as one of the most exciting topics in the science of light, with stunning and unexpected outcomes that have fascinated scientists and the general public alike. This volume details recent advances in the study of optical metamaterials, ranging from fundamental aspects to up-to-date implementations, in one unified treatment. Important recent developments and applications such as superlenses and cloaking devices are also treated in detail and made understandable. Optical Metamaterials will serve as a very timely book for both newcomers and advanced researchers in this rapidly evolving field. Early praise for Optical Metamaterials: "...this book is timely bringing to students and other new entrants to the field the most up to date concepts. Th...

  11. Shape morphing Kirigami mechanical metamaterials.

    Science.gov (United States)

    Neville, Robin M; Scarpa, Fabrizio; Pirrera, Alberto

    2016-08-05

    Mechanical metamaterials exhibit unusual properties through the shape and movement of their engineered subunits. This work presents a new investigation of the Poisson's ratios of a family of cellular metamaterials based on Kirigami design principles. Kirigami is the art of cutting and folding paper to obtain 3D shapes. This technique allows us to create cellular structures with engineered cuts and folds that produce large shape and volume changes, and with extremely directional, tuneable mechanical properties. We demonstrate how to produce these structures from flat sheets of composite materials. By a combination of analytical models and numerical simulations we show how these Kirigami cellular metamaterials can change their deformation characteristics. We also demonstrate the potential of using these classes of mechanical metamaterials for shape change applications like morphing structures.

  12. Hyperbolic Metamaterials with Complex Geometry

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Andryieuski, Andrei; Zhukovsky, Sergei

    2016-01-01

    We investigate new geometries of hyperbolic metamaterialssuch as highly corrugated structures, nanoparticle monolayer assemblies, super-structured or vertically arranged multilayersand nanopillars. All structures retain basic propertiesof hyperbolic metamaterials, but have functionality improved...

  13. Negative index in chiral metamaterials

    OpenAIRE

    Singh, S.; Plum, E.; Menzel, C.; Rockstuhl, C.; Zheludev, N.; Zhang, W.

    2011-01-01

    We demonstrate that planar metamaterial lacking of mirror symmetry shows asymmetric transmission of terahertz waves and bands of positive, negative and zero phase and group velocities indicating a polarization sensitive negative index and slow-light media.

  14. Right-handed double-helix ultrashort DNA yields chiral nematic phases with both right- and left-handed director twist.

    Science.gov (United States)

    Zanchetta, Giuliano; Giavazzi, Fabio; Nakata, Michi; Buscaglia, Marco; Cerbino, Roberto; Clark, Noel A; Bellini, Tommaso

    2010-10-12

    Concentrated solutions of duplex-forming DNA oligomers organize into various mesophases among which is the nematic (N(∗)), which exhibits a macroscopic chiral helical precession of molecular orientation because of the chirality of the DNA molecule. Using a quantitative analysis of the transmission spectra in polarized optical microscopy, we have determined the handedness and pitch of this chiral nematic helix for a large number of sequences ranging from 8 to 20 bases. The B-DNA molecule exhibits a right-handed molecular double-helix structure that, for long molecules, always yields N(∗) phases with left-handed pitch in the μm range. We report here that ultrashort oligomeric duplexes show an extremely diverse behavior, with both left- and right-handed N(∗) helices and pitches ranging from macroscopic down to 0.3 μm. The behavior depends on the length and the sequence of the oligomers, and on the nature of the end-to-end interactions between helices. In particular, the N(∗) handedness strongly correlates with the oligomer length and concentration. Right-handed phases are found only for oligomers shorter than 14 base pairs, and for the sequences having the transition to the N(∗) phase at concentration larger than 620 mg/mL. Our findings indicate that in short DNA, the intermolecular double-helical interactions switch the preferred liquid crystal handedness when the columns of stacked duplexes are forced at high concentrations to separations comparable to the DNA double-helix pitch, a regime still to be theoretically described.

  15. A simple connection of the (electroweak) anapole moment with the (electroweak) charge radius of a massless left-handed Dirac neutrino

    Energy Technology Data Exchange (ETDEWEB)

    Rosado, A. [Universidad Autonoma de Puebla, Puebla (Mexico)

    2001-04-01

    Assuming that the neutrino is a massless left-handed Dirac particle, we show that the neutrino anapole moment and the neutrino charge radius satisfy the simple relation a{sub v} =(r{sup 2}{sub v}) /6, in the context of the Standard Model of the electroweak interactions. We also show that the neutrino electroweak anapole moment a{sub v}l{sup E}W and the neutrino electroweak charge radius (r{sup 2}{sub v}){sup E}W, which have been defined through the v{sub l}l' scattering at the one-loop level and are physical quantities, also obey the relation a{sub v}l{sup E}W =(r{sup 2}{sub v}){sup E}W/6. [Spanish] Suponiendo que el neutrino es una particula de Dirac, sin masa y con helicidad izquierda, mostramos que el momento anapolar a{sub v} y el radio de carga (r{sub v}{sup 2}) del neutrino satisfacen la relacion simple a{sub v} =(r{sup 2}{sub v}) /6, en el contexto del Modelo Estandar de las interacciones electrodebiles. Ademas, mostramos que el momento anapolar electrodebil a{sub v}l{sup E}W y el radio de carga electrodebil (r{sup 2}{sub v}){sup E}W del neutrino, los cuales han sido definidos a traves de la dispersion v{sub l}l' a nivel de un lazo y que son cantidades fisicas, tambien obedecen la relacion a{sub v}l{sup E}W =(r{sup 2}{sub v}){sup E}W/6.

  16. Negotiating Left-Hand and Right-Hand Bends: A Motorcycle Simulator Study to Investigate Experiential and Behaviour Differences Across Rider Groups

    Science.gov (United States)

    Crundall, Elizabeth; Crundall, David; Stedmon, Alex W.

    2012-01-01

    Why do motorcyclists crash on bends? To address this question we examined the riding styles of three groups of motorcyclists on a motorcycle simulator. Novice, experienced and advanced motorcyclists navigated a series of combined left and right bends while their speed and lane position were recorded. Each rider encountered an unexpected hazard on both a left- and right-hand bend section. Upon seeing the hazards, all riders decreased their speed before steering to avoid the hazard. Experienced riders tended to follow more of a racing line through the bends, which resulted in them having to make the most severe changes to their position to avoid a collision. Advanced riders adopted the safest road positions, choosing a position which offered greater visibility through the bends. As a result, they did not need to alter their road position in response to the hazard. Novice riders adopted similar road positions to experienced riders on the left-hand bends, but their road positions were more similar to advanced riders on right-hand bends, suggesting that they were more aware of the risks associated with right bends. Novice riders also adopted a safer position on post-hazard bends whilst the experienced riders failed to alter their behaviour even though they had performed the greatest evasive manoeuvre in response to the hazards. Advanced riders did not need to alter their position as their approach to the bends was already optimal. The results suggest that non-advanced riders were more likely to choose an inappropriate lane position than an inappropriate speed when entering a bend. Furthermore, the findings support the theory that expertise is achieved as a result of relearning, with advanced training overriding ‘bad habits’ gained through experience alone. PMID:22253845

  17. Enhanced parametric processes in binary metamaterials

    OpenAIRE

    Gorkunov, Maxim V.; Shadrivov, Ilya V.; Kivshar, Yuri S.

    2005-01-01

    We suggest double-resonant (binary) metamaterials composed of two types of magnetic resonant elements, and demonstrate that in the nonlinear regime such metamaterials provide unique possibilities for phase-matched parametric interaction and enhanced second-harmonic generation.

  18. Additively manufactured metallic pentamode meta-materials

    NARCIS (Netherlands)

    Hedayati, R.; Leeflang, M.A.; Zadpoor, A.A.

    2017-01-01

    Mechanical metamaterials exhibit unusual mechanical properties that originate from their topological design. Pentamode metamaterials are particularly interesting because they could be designed to possess any thermodynamically admissible elasticity tensor. In this study, we additively manufacture

  19. Shape-matching soft mechanical metamaterials

    NARCIS (Netherlands)

    Mirzaali Mazandarani, M.; Janbaz, S.; Strano, M.; Vergani, L.; Zadpoor, A.A.

    2018-01-01

    Architectured materials with rationally designed geometries could be used to create mechanical metamaterials with unprecedented or rare properties and functionalities. Here, we introduce "shape-matching" metamaterials where the geometry of cellular structures comprising auxetic and conventional

  20. Fractal THz metamaterials

    DEFF Research Database (Denmark)

    Malureanu, Radu; Jepsen, Peter Uhd; Xiao, S.

    2010-01-01

    applications. THz radiation can be employed for various purposes, among them the study of vibrations in biological molecules, motion of electrons in semiconductors and propagation of acoustic shock waves in crystals. We propose here a new THz fractal MTM design that shows very high transmission in the desired...... frequency range as well as a clear differentiation between one polarisation and another. Based on theoretical predictions we fabricated and measured a fractal based THz metamaterial that shows more than 60% field transmission at around 1THz for TE polarized light while the TM waves have almost 80% field...... transmission peak at 0.6THz. One of the main characteristics of this design is its tunability by design: by simply changing the length of the fractal elements one can choose the operating frequency window. The modelling, fabrication and characterisation results will be presented in this paper. Due to the long...

  1. Doped Chiral Polymer Metamaterials

    Science.gov (United States)

    Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Gordon, Keith L. (Inventor); Sauti, Godfrey (Inventor); Lowther, Sharon E. (Inventor); Bryant, Robert G. (Inventor)

    2017-01-01

    Some implementations provide a composite material that includes a first material and a second material. In some implementations, the composite material is a metamaterial. The first material includes a chiral polymer (e.g., crystalline chiral helical polymer, poly-.gamma.-benzyl-L-glutamate (PBLG), poly-L-lactic acid (PLA), polypeptide, and/or polyacetylene). The second material is within the chiral polymer. The first material and the second material are configured to provide an effective index of refraction value for the composite material of 1 or less. In some implementations, the effective index of refraction value for the composite material is negative. In some implementations, the effective index of refraction value for the composite material of 1 or less is at least in a wavelength of one of at least a visible spectrum, an infrared spectrum, a microwave spectrum, and/or an ultraviolet spectrum.

  2. Waves in metamaterials

    CERN Document Server

    Solymar, Laszlo

    2014-01-01

    Metamaterials is a young subject born in the 21st century. It is concerned with artificial materials which can have electrical and magnetic properties difficult or impossible to find in nature. The building blocks in most cases are resonant elements much smaller than the wavelength of the electromagnetic wave. The book offers a comprehensive treatment of all aspects of research in this field at a level that should appeal to final year undergraduates in physics or in electrical and electronic engineering. The mathematics is kept at a minimum; the aim is to explain the physics in simple terms and enumerate the major advances. It can be profitably read by graduate and post-graduate students in order to find out what has been done in the field outside their speciality, and by experts who may gain new insight about the inter-relationship of the physical phenomena involved.

  3. Metamaterials for perfect absorption

    CERN Document Server

    Lee, Young Pak; Yoo, Young Joon; Kim, Ki Won

    2016-01-01

    This book provides a comprehensive overview of the theory and practical development of metamaterial-based perfect absorbers (MMPAs). It begins with a brief history of MMPAs which reviews the various theoretical and experimental milestones in their development. The theoretical background and fundamental working principles of MMPAs are then discussed, providing the necessary background on how MMPAs work and are constructed. There then follows a section describing how different MMPAs are designed and built according to the operating frequency of the electromagnetic wave, and how their behavior is changed. Methods of fabricating and characterizing MMPAs are then presented. The book elaborates on the performance and characteristics of MMPAs, including electromagnetically-induced transparency (EIT). It also covers recent advances in MMPAs and their applications, including multi-band, broadband, tunability, polarization independence and incidence independence. Suitable for graduate students in optical sciences and e...

  4. Using enveloping distribution sampling to compute the free enthalpy difference between right- and left-handed helices of a β-peptide in solution.

    Science.gov (United States)

    Lin, Zhixiong; Timmerscheidt, Tobias A; van Gunsteren, Wilfred F

    2012-08-14

    Recently, the method of enveloping distribution sampling (EDS) to efficiently obtain free enthalpy differences between different molecular systems from a single simulation has been generalized to compute free enthalpy differences between different conformations of a system [Z. X. Lin, H. Y. Liu, S. Riniker, and W. F. van Gunsteren, J. Chem. Theory Comput. 7, 3884 (2011)]. However, the efficiency of EDS in this case is hampered if the parts of the conformational space relevant to the two end states or conformations are far apart and the conformational diffusion from one state to the other is slow. This leads to slow convergence of the EDS parameter values and free enthalpy differences. In the present work, we apply the EDS methodology to a challenging case, i.e., to calculate the free enthalpy difference between a right-handed 2.7(10∕12)-helix and a left-handed 3(14)-helix of a hexa-β-peptide in solution from a single simulation. No transition between the two helices was detected in a standard EDS parameter update simulation, thus enhanced sampling techniques had to be applied, which included adiabatic decoupling (AD) of solute and solvent motions in combination with increasing the solute temperature, and lowering the shear viscosity of the solvent. AD was found to be unsuitable to enhance the sampling of the solute conformations in the EDS parameter update simulations. Lowering the solvent shear viscosity turned out to be useful during EDS parameter update simulations, i.e., it did speed up the conformational diffusion of the solute, more transitions between the two helices were observed. This came at the cost of more CPU time spent due to the shorter time step needed for simulations with the lower solvent shear viscosity. Using an improved EDS parameter update scheme, parameter convergence was five-fold enhanced. The resulting free enthalpy difference between the two helices calculated from EDS agrees well with the result obtained through direct counting from a

  5. Structure of the hypothetical protein Ton1535 from Thermococcus onnurineus NA1 reveals unique structural properties by a left-handed helical turn in normal α-solenoid protein.

    Science.gov (United States)

    Jeong, Jae-Hee; Kim, Yi-Seul; Rojvirija, Catleya; Cha, Hyung Jin; Kim, Yeon-Gil; Ha, Sung Chul

    2014-06-01

    The crystal structure of Ton1535, a hypothetical protein from Thermococcus onnurineus NA1, was determined at 2.3 Å resolution. With two antiparallel α-helices in a helix-turn-helix motif as a repeating unit, Ton1535 consists of right-handed coiled N- and C-terminal regions that are stacked together using helix bundles containing a left-handed helical turn. One left-handed helical turn in the right-handed coiled structure produces two unique structural properties. One is the presence of separated concave grooves rather than one continuous concave groove, and the other is the contribution of α-helices on the convex surfaces of the N-terminal region to the extended surface of the concave groove of the C-terminal region and vice versa. © 2013 Wiley Periodicals, Inc.

  6. Numerical methods for metamaterial design

    CERN Document Server

    2013-01-01

    This book describes a relatively new approach for the design of electromagnetic metamaterials.  Numerical optimization routines are combined with electromagnetic simulations to tailor the broadband optical properties of a metamaterial to have predetermined responses at predetermined wavelengths. After a review of both the major efforts within the field of metamaterials and the field of mathematical optimization, chapters covering both gradient-based and derivative-free design methods are considered.  Selected topics including surrogate-base optimization, adaptive mesh search, and genetic algorithms are shown to be effective, gradient-free optimization strategies.  Additionally, new techniques for representing dielectric distributions in two dimensions, including level sets, are demonstrated as effective methods for gradient-based optimization.  Each chapter begins with a rigorous review of the optimization strategy used, and is followed by numerous examples that combine the strategy with either electromag...

  7. Nonlinear, tunable and active metamaterials

    CERN Document Server

    Lapine, Mikhail; Kivshar, Yuri

    2015-01-01

    Metamaterials, artificial electromagnetic media achieved by structuring on the subwave-length-scale were initially suggested for the negative index and superlensing. They became a paradigm for engineering electromagnetic space and controlling propagation of waves. The research agenda is now shifting on achieving tuneable, switchable, nonlinear and sensing functionalities. The time has come to talk about the emerging research field of metadevices employing active and tunable metamaterials with unique functionalities achieved by structuring of functional matter on the subwave-length scale. This book presents the first systematic and comprehensive summary of the reviews written by the pioneers and top-class experts in the field of metamaterials. It addresses many grand challenges of the cutting edge research for creating smaller and more efficient photonic structures and devices.

  8. Crystal structure of the left-handed archaeal RadA helical filament: identification of a functional motif for controlling quaternary structures and enzymatic functions of RecA family proteins

    Science.gov (United States)

    Chen, Li-Tzu; Ko, Tzu-Ping; Chang, Yuan-Chih; Lin, Kuei-An; Chang, Chia-Seng; Wang, Andrew H.-J.; Wang, Ting-Fang

    2007-01-01

    The RecA family of proteins mediates homologous recombination, an evolutionarily conserved pathway that maintains genomic stability by protecting against DNA double strand breaks. RecA proteins are thought to facilitate DNA strand exchange reactions as closed-rings or as right-handed helical filaments. Here, we report the crystal structure of a left-handed Sulfolobus solfataricus RadA helical filament. Each protomer in this left-handed filament is linked to its neighbour via interactions of a β-strand polymerization motif with the neighbouring ATPase domain. Immediately following the polymerization motif, we identified an evolutionarily conserved hinge region (a subunit rotation motif) in which a 360° clockwise axial rotation accompanies stepwise structural transitions from a closed ring to the AMP–PNP right-handed filament, then to an overwound right-handed filament and finally to the left-handed filament. Additional structural and functional analyses of wild-type and mutant proteins confirmed that the subunit rotation motif is crucial for enzymatic functions of RecA family proteins. These observations support the hypothesis that RecA family protein filaments may function as rotary motors. PMID:17329376

  9. Periodic waves in nonlinear metamaterials

    International Nuclear Information System (INIS)

    Liu, Wen-Jun; Xiao, Jing-Hua; Yan, Jie-Yun; Tian, Bo

    2012-01-01

    Periodic waves are presented in this Letter. With symbolic computation, equations for monochromatic waves are studied, and analytic periodic waves are obtained. Factors affecting properties of periodic waves are analyzed. Nonlinear metamaterials, with the continuous distribution of the dielectric permittivity obtained, are different from the ones with the discrete distribution. -- Highlights: ► Equations for the monochromatic waves in transverse magnetic polarization have been studied. ► Analytic periodic waves for the equations have been obtained. ► Periodic waves are theoretically presented and studied in the nonlinear metamaterials.

  10. Topological Gyroscopic Metamaterials

    Science.gov (United States)

    Nash, Lisa Michelle

    Topological materials are generally insulating in their bulk, with protected conducting states on their boundaries that are robust against disorder and perturbation of material property. The existence of these conducting edge states is characterized by an integer topological invariant. Though the phenomenon was first discovered in electronic systems, recent years have shown that topological states exist in classical systems as well. In this thesis we are primarily concerned with the topological properties of gyroscopic materials, which are created by coupling networks of fast-spinning objects. Through a series of simulations, numerical calculations, and experiments, we show that these materials can support topological edge states. We find that edge states in these gyroscopic metamaterials bear the hallmarks of topology related to broken time reversal symmetry: they transmit excitations unidirectionally and are extremely robust against experimental disorder. We also explore requirements for topology by studying several lattice configurations and find that topology emerges naturally in gyroscopic systems.A simple prescription can be used to create many gyroscopic lattices. Though many of our gyroscopic networks are periodic, we explore amorphous point-sets and find that topology also emerges in these networks.

  11. Confinement of light in periodic structures with negative phase velocity

    International Nuclear Information System (INIS)

    Driss Bria; Abdelmajid Essadqui; Bahram Djafari-Rouhani; Mohamed Azizi; Abdellah Daoudi; Abdelkrim Nougaoui

    2008-08-01

    We discuss unusual features of wave propagation in periodic arrays of slabs made of transparent left-handed metamaterials with simultaneously negative dielectric permittivity and magnetic permeability, and demonstrate the possibility of light confinement due to the appearance of complete photonic band-gaps in such one-dimensional structures. With an appropriate choice of the parameters, we show that it is possible to realize an absolute (or omnidirectional) band gap for either transverse electric (TE) or transverse magnetic (TM) polarizations of the electromagnetic waves. A combination of two multilayer structures composed of right-handed material (RHM) and left-handed metamaterials LHM is proposed to realize, in a certain range of frequency, an omnidirectional reflector of light for both polarizations. (author)

  12. Wave propagation in mechanical metamaterials

    NARCIS (Netherlands)

    Zhou, Y.

    2017-01-01

    In mechanical metamaterials, large deformations can occur in systems which are topological from the point of view of linear waves. The interplay between such nonlinearities and topology affects wave propagation. Beyond perfectly periodic systems, defects provide a way to modify and control

  13. Mimicking Celestial Mechanics in Metamaterials

    Science.gov (United States)

    2009-09-01

    general theory of relativity is the bending of light that passes near massive celestial objects such as stars, nebulas or galaxies . This effect...optical metamaterial exhibiting negative refractive index. Nature 455, 376–379 (2008). 14. Shapiro, S. L. & Teukolsky, S. A.White Dwarfs , and Neutron

  14. Homogenization scheme for acoustic metamaterials

    KAUST Repository

    Yang, Min

    2014-02-26

    We present a homogenization scheme for acoustic metamaterials that is based on reproducing the lowest orders of scattering amplitudes from a finite volume of metamaterials. This approach is noted to differ significantly from that of coherent potential approximation, which is based on adjusting the effective-medium parameters to minimize scatterings in the long-wavelength limit. With the aid of metamaterials’ eigenstates, the effective parameters, such as mass density and elastic modulus can be obtained by matching the surface responses of a metamaterial\\'s structural unit cell with a piece of homogenized material. From the Green\\'s theorem applied to the exterior domain problem, matching the surface responses is noted to be the same as reproducing the scattering amplitudes. We verify our scheme by applying it to three different examples: a layered lattice, a two-dimensional hexagonal lattice, and a decorated-membrane system. It is shown that the predicted characteristics and wave fields agree almost exactly with numerical simulations and experiments and the scheme\\'s validity is constrained by the number of dominant surface multipoles instead of the usual long-wavelength assumption. In particular, the validity extends to the full band in one dimension and to regimes near the boundaries of the Brillouin zone in two dimensions.

  15. Designing perturbative metamaterials from discrete models.

    Science.gov (United States)

    Matlack, Kathryn H; Serra-Garcia, Marc; Palermo, Antonio; Huber, Sebastian D; Daraio, Chiara

    2018-04-01

    Identifying material geometries that lead to metamaterials with desired functionalities presents a challenge for the field. Discrete, or reduced-order, models provide a concise description of complex phenomena, such as negative refraction, or topological surface states; therefore, the combination of geometric building blocks to replicate discrete models presenting the desired features represents a promising approach. However, there is no reliable way to solve such an inverse problem. Here, we introduce 'perturbative metamaterials', a class of metamaterials consisting of weakly interacting unit cells. The weak interaction allows us to associate each element of the discrete model with individual geometric features of the metamaterial, thereby enabling a systematic design process. We demonstrate our approach by designing two-dimensional elastic metamaterials that realize Veselago lenses, zero-dispersion bands and topological surface phonons. While our selected examples are within the mechanical domain, the same design principle can be applied to acoustic, thermal and photonic metamaterials composed of weakly interacting unit cells.

  16. Electrifying photonic metamaterials for tunable nonlinear optics.

    Science.gov (United States)

    Kang, Lei; Cui, Yonghao; Lan, Shoufeng; Rodrigues, Sean P; Brongersma, Mark L; Cai, Wenshan

    2014-08-11

    Metamaterials have not only enabled unprecedented flexibility in producing unconventional optical properties that are not found in nature, they have also provided exciting potential to create customized nonlinear media with high-order properties correlated to linear behaviour. Two particularly compelling directions are active metamaterials, whose optical properties can be purposely tailored by external stimuli in a reversible manner, and nonlinear metamaterials, which enable intensity-dependent frequency conversion of light waves. Here, by exploring the interaction of these two directions, we leverage the electrical and optical functions simultaneously supported in nanostructured metals and demonstrate electrically controlled nonlinear optical processes from a metamaterial. Both second harmonic generation and optical rectification, enhanced by the resonance behaviour in the metamaterial absorber, are modulated externally with applied voltage signals. Our results reveal an opportunity to exploit optical metamaterials as self-contained, dynamic electro-optic systems with intrinsically embedded electrical functions and optical nonlinearities.

  17. Casimir interactions between graphene sheets and metamaterials

    International Nuclear Information System (INIS)

    Drosdoff, D.; Woods, Lilia M.

    2011-01-01

    The Casimir force between graphene sheets and metamaterials is studied. Theoretical results based on the Lifshitz theory for layered, planar, two-dimensional systems in media are presented. We consider graphene-graphene, graphene-metamaterial, and metal-graphene-metamaterial configurations. We find that quantum effects of the temperature-dependent force are not apparent until the submicron range. In contrast to results with bulk dielectric and bulk metallic materials, no Casimir repulsion is found when graphene is placed on top of a magnetically active metamaterial substrate, regardless of the strength of the low-frequency magnetic response. In the case of the metal-graphene-metamaterial setting, repulsion between the metamaterial and the metal-graphene system is possible only when the dielectric response from the metal contributes significantly.

  18. Multiband Negative Permittivity Metamaterials and Absorbers

    Directory of Open Access Journals (Sweden)

    Yiran Tian

    2013-01-01

    Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

  19. Towards three-dimensional optical metamaterials

    Science.gov (United States)

    Tanaka, Takuo; Ishikawa, Atsushi

    2017-12-01

    Metamaterials have opened up the possibility of unprecedented and fascinating concepts and applications in optics and photonics. Examples include negative refraction, perfect lenses, cloaking, perfect absorbers, and so on. Since these metamaterials are man-made materials composed of sub-wavelength structures, their development strongly depends on the advancement of micro- and nano-fabrication technologies. In particular, the realization of three-dimensional metamaterials is one of the big challenges in this research field. In this review, we describe recent progress in the fabrication technologies for three-dimensional metamaterials, as well as proposed applications.

  20. Towards three-dimensional optical metamaterials.

    Science.gov (United States)

    Tanaka, Takuo; Ishikawa, Atsushi

    2017-01-01

    Metamaterials have opened up the possibility of unprecedented and fascinating concepts and applications in optics and photonics. Examples include negative refraction, perfect lenses, cloaking, perfect absorbers, and so on. Since these metamaterials are man-made materials composed of sub-wavelength structures, their development strongly depends on the advancement of micro- and nano-fabrication technologies. In particular, the realization of three-dimensional metamaterials is one of the big challenges in this research field. In this review, we describe recent progress in the fabrication technologies for three-dimensional metamaterials, as well as proposed applications.

  1. Metamaterial-enabled transformation optics

    Science.gov (United States)

    Landy, Nathan

    Transformation Optics is a design methodology that uses the form invariance of Maxwell's equations to distort electromagnetic fields. This distortion is imposed on a region of space by mimicking a curvilinear coordinate system with prescribed magnetoelectric material parameters. By simply specifying the correct coordinate transformation, researchers have created such exotic devices as invisibility cloaks, ``perfect'' lenses, and illusion devices. Unfortunately, these devices typically require correspondingly exotic material parameters that do not occur in Nature. Researchers have therefore turned to complex artificial media known as metamaterials to approximate the desired responses. However, the metamaterial design process is complex, and there are limitations on the responses that they achieve. In this dissertation, we explore both the applicability and limitations of metamaterials in Transformation Optics design. We begin in Chapter 2 by investigating the freedoms available to use in the transformation optics design process itself. We show that quasi-conformal mappings may be used to alleviate some of the complexity of material design in both two- and three-dimensional design. We then go on in Chapter 3 to apply this method to the design of a transformation-optics modified optic. We show that even a highly-approximate implementation of such a lens would retain many of the key performance feautures that we would expect from a full material prescription. However, the approximations made in the design of our lens may not be valid in other areas of transformation optical design. For instance, the high-frequency approximations of our lens design ignore the effects of impedance mismatch, and the approximation is not valid when the material parameters vary on the order of a wavelength. Therefore, in Chapter 4 we use other freedoms available to us to design a full-parameter cloak of invisibility. By tailoring the electromagnetic environment of our cloak, we are able to

  2. Perspective: Acoustic metamaterials in transition

    KAUST Repository

    Wu, Ying

    2017-12-15

    Acoustic metamaterials derive their novel characteristics from the interaction between acoustic waves with designed structures. Since its inception seventeen years ago, the field has been driven by fundamental geometric and physical principles that guide the structure design rules as well as provide the basis for wave functionalities. Recent examples include resonance-based acoustic metasurfaces that offer flexible control of acoustic wave propagation such as focusing and re-direction; parity-time (PT)-symmetric acoustics that utilizes the general concept of pairing loss and gain to achieve perfect absorption at a single frequency; and topological phononics that can provide one-way edge state propagation. However, such novel functionalities are not without constraints. Metasurface elements rely on resonances to enhance their coupling to the incident wave; hence, its functionality is limited to a narrow frequency band. Topological phononics is the result of the special lattice symmetry that must be fixed at the fabrication stage. Overcoming such constraints naturally forms the basis for further developments. We identify two emergent directions: Integration of acoustic metamaterial elements for achieving broadband characteristics as well as acoustic wave manipulation tasks more complex than the single demonstrative functionality; and active acoustic metamaterials that can adapt to environment as well as to go beyond the constraints on the passive acoustic metamaterials. Examples of a successful recent integration of multi-resonators in achieving broadband sound absorption can be found in optimal sound-absorbing structures, which utilize causality constraint as a design tool in realizing the target-set absorption spectrum with a minimal sample thickness. Active acoustic metamaterials have also demonstrated the capability to tune bandgaps as well as to alter property of resonances in real time through stiffening of the spring constants, in addition to the PT symmetric

  3. Metamaterials: a new frontier of science and technology.

    Science.gov (United States)

    Liu, Yongmin; Zhang, Xiang

    2011-05-01

    Metamaterials, artificial composite structures with exotic material properties, have emerged as a new frontier of science involving physics, material science, engineering and chemistry. This critical review focuses on the fundamentals, recent progresses and future directions in the research of electromagnetic metamaterials. An introduction to metamaterials followed by a detailed elaboration on how to design unprecedented electromagnetic properties of metamaterials is presented. A number of intriguing phenomena and applications associated with metamaterials are discussed, including negative refraction, sub-diffraction-limited imaging, strong optical activities in chiral metamaterials, interaction of meta-atoms and transformation optics. Finally, we offer an outlook on future directions of metamaterials research including but not limited to three-dimensional optical metamaterials, nonlinear metamaterials and "quantum" perspectives of metamaterials (142 references).

  4. Acoustic metamaterials with synergetic coupling

    Science.gov (United States)

    Ma, Fuyin; Huang, Meng; Wu, Jiu Hui

    2017-12-01

    In this paper, we propose a general design concept for acoustic metamaterials that introduces a ubiquitous synergetic behavior into the design procedure, in which the structure of the design is driven by its functional requirements. Since the physical properties of the widely used, resonant-type metamaterials are mainly determined by the eigenmodes of the structure, we first introduce the design concept through the modal displacement distributions on two typical plate-type structures. Next, by employing broadband sound attenuations that involve both the insulation and absorption as the typical targets, two synergetic coupling behaviors are systematically revealed among the dense resonant modes and multi-cell. Furthermore, through plate-type multiple-cell structures assembled from nine oscillators, the design is shown to realize strong broadband attenuations with either the average sound transmission loss (STL) below 2000 Hz higher than 40 dB or the absorption approximately 0.99 in the range of 400-700 Hz wherein the average absorption below 800 Hz remains higher than 0.8. Finally, two multi-cell plate-type samples are fabricated and then used experimentally to measure the STLs in support of the proposed synergetic coupling design method. Both the computational and experimental results demonstrate that the proposed synergetic design concept could effectively initiate a design for metamaterials that offer a new degree of freedom for broadband sound attenuations.

  5. Isotropic Negative Thermal Expansion Metamaterials.

    Science.gov (United States)

    Wu, Lingling; Li, Bo; Zhou, Ji

    2016-07-13

    Negative thermal expansion materials are important and desirable in science and engineering applications. However, natural materials with isotropic negative thermal expansion are rare and usually unsatisfied in performance. Here, we propose a novel method to achieve two- and three-dimensional negative thermal expansion metamaterials via antichiral structures. The two-dimensional metamaterial is constructed with unit cells that combine bimaterial strips and antichiral structures, while the three-dimensional metamaterial is fabricated by a multimaterial 3D printing process. Both experimental and simulation results display isotropic negative thermal expansion property of the samples. The effective coefficient of negative thermal expansion of the proposed models is demonstrated to be dependent on the difference between the thermal expansion coefficient of the component materials, as well as on the circular node radius and the ligament length in the antichiral structures. The measured value of the linear negative thermal expansion coefficient of the three-dimensional sample is among the largest achieved in experiments to date. Our findings provide an easy and practical approach to obtaining materials with tunable negative thermal expansion on any scale.

  6. Generalized metamaterials: Definitions and taxonomy.

    Science.gov (United States)

    Kim, Noori; Yoon, Yong-Jin; Allen, Jont B

    2016-06-01

    This article reviews the development of metamaterials (MM), starting from Newton's discovery of the wave equation, and ends with a discussion of the need for a technical taxonomy (classification) of these materials, along with a better defined definition of metamaterials. It is intended to be a technical definition of metamaterials, based on a historical perspective. The evolution of MMs began with the discovery of the wave equation, traceable back to Newton's calculation of the speed of sound. The theory of sound evolved to include quasi-statics (Helmholtz) and the circuit equations of Kirchhoff's circuit laws, leading to the ultimate development of Maxwell's equations and the equation for the speed of light. Be it light, or sound, the speed of the wave-front travel defines the wavelength, and thus the quasi-static (QS) approximation. But there is much more at stake than QSs. Taxonomy requires a proper statement of the laws of physics, which includes at least the six basic network postulates: (P1) causality (non-causal/acausal), (P2) linearity (non-linear), (P3) real (complex) time response, (P4) passive (active), (P5) time-invariant (time varying), and (P6) reciprocal (non-reciprocal). These six postulates are extended to include MMs.

  7. Beyond local effective material properties for metamaterials

    Science.gov (United States)

    Mnasri, K.; Khrabustovskyi, A.; Stohrer, C.; Plum, M.; Rockstuhl, C.

    2018-02-01

    To discuss the properties of metamaterials on physical grounds and to consider them in applications, effective material parameters are usually introduced and assigned to a given metamaterial. In most cases, only weak spatial dispersion is considered. It allows to assign local material properties, e.g., a permittivity and a permeability. However, this turned out to be insufficient. To solve this problem, we study here the effective properties of metamaterials with constitutive relations beyond a local response and take strong spatial dispersion into account. This research requires two contributions. First, bulk properties in terms of eigenmodes need to be studied. We particularly investigate the isofrequency surfaces of their dispersion relation are investigated and compared to those of an actual metamaterial. The significant improvement to effectively describe it provides evidence for the necessity to use nonlocal material laws in the effective description of metamaterials. Second, to be able to capitalize on such constitutive relations, also interface conditions need to be known. They are derived in this contribution for our form of the nonlocality using a generalized (weak) formulation of Maxwell's equations. Based on such interface conditions, Fresnel expressions are obtained that predict the amplitude of the reflected and transmitted plane wave upon illuminating a slab of such a nonlocal metamaterial. This all together offers the necessary means for the in-depth analysis of metamaterials characterized by strong spatial dispersion. The general formulation we choose here renders our approach applicable to a wide class of metamaterials.

  8. Optical properties of nanowire metamaterials with gain

    DEFF Research Database (Denmark)

    Isidio de Lima, Joaquim Junior; Adam, Jost; Rego, Davi

    2016-01-01

    The transmittance, reflectance and absorption of a nanowire metamaterial with optical gain are numerically simulated and investigated. It is assumed that the metamaterial is represented by aligned silver nanowires embedded into a semiconductor matrix, made of either silicon or gallium phosphide...

  9. Tunable VO2/Au Hyperbolic Metamaterial

    Science.gov (United States)

    2016-02-12

    Ziolkowski, Metamaterials: Physics and Engineering Explorations ( John Wiley & Sons, 2006). 4M. A. Noginov and V. A. Podolskiy , Tutorials in Metamaterials... Dryden , G. Nataraj, G. Zhu and E. E. Narimanov, Opt. Lett. 35, 1863-1865 (2010).18a T. Tumkur, G. Zhu, P. Black, Y. A. Barnakov, C. E. Bonner and M. A

  10. Coaxial plasmonic metamaterials for visible light

    NARCIS (Netherlands)

    van de Haar, M.A.

    2016-01-01

    Optical metamaterials are materials built from sub-wavelength building blocks, and can be designed to have effective optical properties that are not found in natural materials. A much-studied class of metamaterials uses small noble-metal resonant structures as building blocks, which have a

  11. Tunable metamaterials fabricated by fiber drawing

    DEFF Research Database (Denmark)

    Fleming, Simon; Stefani, Alessio; Tang, Xiaoli

    2017-01-01

    We demonstrate a practical scalable approach to the fabrication of tunable metamaterials. Designed for terahertz (THz) wavelengths, the metamaterial is comprised of polyurethane filled with an array of indium wires using the well-established fiber drawing technique. Modification of the dimensions...

  12. Tunable microwave metamaterials based on ordinary water

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei V.; Jacobsen, Rasmus Elkjær; Arslanagic, Samel

    All-dielectric metamaterials are the growing trend in optics and electromagnetics. They require materials with high permittivity, for example silicon in photonics. Aiming the microwaves range we present here water as a unique substance for employing in metamaterials design. Dependence of water...

  13. Metamaterial Resonant Absorbers for Terahertz Sensing

    Science.gov (United States)

    2015-12-01

    process was completed in the NPS clean room for an Al/SiOx/Al metamaterial absorber . After fabrication, FTIR testing was employed to determine the...is unlimited METAMATERIAL RESONANT ABSORBERS FOR TERAHERTZ SENSING by Eric A. Stinson December 2015 Thesis Advisor: Gamani Karunasiri...

  14. Water based fluidic radio frequency metamaterials

    Science.gov (United States)

    Cai, Xiaobing; Zhao, Shaolin; Hu, Mingjun; Xiao, Junfeng; Zhang, Naibo; Yang, Jun

    2017-11-01

    Electromagnetic metamaterials offer great flexibility for wave manipulation and enable exceptional functionality design, ranging from negative refraction, anomalous reflection, super-resolution imaging, transformation optics to cloaking, etc. However, demonstration of metamaterials with unprecedented functionalities is still challenging and costly due to the structural complexity or special material properties. Here, we demonstrate for the first time the versatile fluidic radio frequency metamaterials with negative refraction using a water-embedded and metal-coated 3D architecture. Effective medium analysis confirms that metallic frames create an evanescent environment while simultaneously water cylinders produce negative permeability under Mie resonance. The water-metal coupled 3D architectures and the accessory devices for measurement are fabricated by 3D printing with post electroless deposition. Our study also reveals the great potential of fluidic metamaterials and versatility of the 3D printing process in rapid prototyping of customized metamaterials.

  15. Inverse Doppler Effects in Broadband Acoustic Metamaterials.

    Science.gov (United States)

    Zhai, S L; Zhao, X P; Liu, S; Shen, F L; Li, L L; Luo, C R

    2016-08-31

    The Doppler effect refers to the change in frequency of a wave source as a consequence of the relative motion between the source and an observer. Veselago theoretically predicted that materials with negative refractions can induce inverse Doppler effects. With the development of metamaterials, inverse Doppler effects have been extensively investigated. However, the ideal material parameters prescribed by these metamaterial design approaches are complex and also challenging to obtain experimentally. Here, we demonstrated a method of designing and experimentally characterising arbitrary broadband acoustic metamaterials. These omni-directional, double-negative, acoustic metamaterials are constructed with 'flute-like' acoustic meta-cluster sets with seven double meta-molecules; these metamaterials also overcome the limitations of broadband negative bulk modulus and mass density to provide a region of negative refraction and inverse Doppler effects. It was also shown that inverse Doppler effects can be detected in a flute, which has been popular for thousands of years in Asia and Europe.

  16. Nondispersive optical activity of meshed helical metamaterials.

    Science.gov (United States)

    Park, Hyun Sung; Kim, Teun-Teun; Kim, Hyeon-Don; Kim, Kyungjin; Min, Bumki

    2014-11-17

    Extreme optical properties can be realized by the strong resonant response of metamaterials consisting of subwavelength-scale metallic resonators. However, highly dispersive optical properties resulting from strong resonances have impeded the broadband operation required for frequency-independent optical components or devices. Here we demonstrate that strong, flat broadband optical activity with high transparency can be obtained with meshed helical metamaterials in which metallic helical structures are networked and arranged to have fourfold rotational symmetry around the propagation axis. This nondispersive optical activity originates from the Drude-like response as well as the fourfold rotational symmetry of the meshed helical metamaterials. The theoretical concept is validated in a microwave experiment in which flat broadband optical activity with a designed magnitude of 45° per layer of metamaterial is measured. The broadband capabilities of chiral metamaterials may provide opportunities in the design of various broadband optical systems and applications.

  17. Hyperbolic metamaterials: Novel physics and applications

    Science.gov (United States)

    Smolyaninov, Igor I.; Smolyaninova, Vera N.

    2017-10-01

    Hyperbolic metamaterials were originally introduced to overcome the diffraction limit of optical imaging. Soon thereafter it was realized that hyperbolic metamaterials demonstrate a number of novel phenomena resulting from the broadband singular behavior of their density of photonic states. These novel phenomena and applications include super resolution imaging, new stealth technologies, enhanced quantum-electrodynamic effects, thermal hyperconductivity, superconductivity, and interesting gravitation theory analogues. Here we briefly review typical material systems, which exhibit hyperbolic behavior and outline important novel applications of hyperbolic metamaterials. In particular, we will describe recent imaging experiments with plasmonic metamaterials and novel VCSEL geometries, in which the Bragg mirrors may be engineered in such a way that they exhibit hyperbolic metamaterial properties in the long wavelength infrared range, so that they may be used to efficiently remove excess heat from the laser cavity. We will also discuss potential applications of three-dimensional self-assembled photonic hypercrystals, which are based on cobalt ferrofluids in external magnetic field. This system bypasses 3D nanofabrication issues, which typically limit metamaterial applications. Photonic hypercrystals combine the most interesting features of hyperbolic metamaterials and photonic crystals.

  18. Generalized field-transforming metamaterials

    International Nuclear Information System (INIS)

    Tretyakov, Sergei A; Nefedov, Igor S; Alitalo, Pekka

    2008-01-01

    In this paper, we introduce a generalized concept of field-transforming metamaterials, which perform field transformations defined as linear relations between the original and transformed fields. These artificial media change the fields in a prescribed fashion in the volume occupied by the medium. We show what electromagnetic properties of transforming medium are required. The coefficients of these linear functions can be arbitrary scalar functions of position and frequency, which makes the approach quite general and opens a possibility to realize various unusual devices.

  19. Aluminum plasmonic metamaterials for structural color printing.

    Science.gov (United States)

    Cheng, Fei; Gao, Jie; Stan, Liliana; Rosenmann, Daniel; Czaplewski, David; Yang, Xiaodong

    2015-06-01

    We report a structural color printing platform based on aluminum plasmonic metamaterials supporting near perfect light absorption and narrow-band spectral response tunable across the visible spectrum to realize high-resolution, angle-insensitive color printing with high color purity and saturation. Additionally, the fabricated metamaterials can be protected by a transparent polymer thin layer for ambient use with further improved color performance. The demonstrated structural color printing with aluminum plasmonic metamaterials offers great potential for relevant applications such as security marking and information storage.

  20. Reconfigurable metamaterials for terahertz wave manipulation

    Science.gov (United States)

    Hashemi, Mohammed R.; Cakmakyapan, Semih; Jarrahi, Mona

    2017-09-01

    Reconfigurable metamaterials have emerged as promising platforms for manipulating the spectral and spatial properties of terahertz waves without being limited by the characteristics of naturally existing materials. Here, we present a comprehensive overview of various types of reconfigurable metamaterials that are utilized to manipulate the intensity, phase, polarization, and propagation direction of terahertz waves. We discuss various reconfiguration mechanisms based on optical, electrical, thermal, and mechanical stimuli while using semiconductors, superconductors, phase-change materials, graphene, and electromechanical structures. The advantages and disadvantages of different reconfigurable metamaterial designs in terms of modulation efficiency, modulation bandwidth, modulation speed, and system complexity are discussed in detail.

  1. Hot carrier metamaterial detectors and energy converters

    Science.gov (United States)

    Krayer, Lisa; Munday, Jeremy N.

    Metamaterials can be used to manipulate the flow of light in ways not typically available with traditional materials. Beyond their optical properties, metamaterials can be used as the basis for optoelectronic devices through the incorporation of a metal-semiconductor interface. The absorbed radiation in the metal can excite surface plasmons, which nonradiatively decay into hot electrons or holes that can be injected into the base semiconductor and contribute to photocurrent generation. In this talk, we will present our latest work on metamaterial photo-detectors and solar energy converters.

  2. Compact Single-Layer Traveling-Wave Antenna DesignUsing Metamaterial Transmission Lines

    Science.gov (United States)

    Alibakhshikenari, Mohammad; Virdee, Bal Singh; Limiti, Ernesto

    2017-12-01

    This paper presents a single-layer traveling-wave antenna (TWA) that is based on composite right/left-handed (CRLH)-metamaterial (MTM) transmission line (TL) structure, which is implemented by using a combination of interdigital capacitors and dual-spiral inductive slots. By embedding dual-spiral inductive slots inside the CRLH MTM-TL results in a compact TWA. Dimensions of the proposed CRLH MTM-TL TWA is 21.5 × 30.0 mm2 or 0.372λ0 × 0.520λ0 at 5.2 GHz (center frequency). The fabricated TWA operates over 1.8-8.6 GHz with a fractional bandwidth greater than 120%, and it exhibits a peak gain and radiation efficiency of 4.2 dBi and 81%, respectively, at 5 GHz. By avoiding the use of lumped components, via-holes or defected ground structures, the proposed TWA design is economic for mass production as well as easy to integrate with wireless communication systems.

  3. Auxetic metamaterials from disordered networks.

    Science.gov (United States)

    Reid, Daniel R; Pashine, Nidhi; Wozniak, Justin M; Jaeger, Heinrich M; Liu, Andrea J; Nagel, Sidney R; de Pablo, Juan J

    2018-02-13

    Recent theoretical work suggests that systematic pruning of disordered networks consisting of nodes connected by springs can lead to materials that exhibit a host of unusual mechanical properties. In particular, global properties such as Poisson's ratio or local responses related to deformation can be precisely altered. Tunable mechanical responses would be useful in areas ranging from impact mitigation to robotics and, more generally, for creation of metamaterials with engineered properties. However, experimental attempts to create auxetic materials based on pruning-based theoretical ideas have not been successful. Here we introduce a more realistic model of the networks, which incorporates angle-bending forces and the appropriate experimental boundary conditions. A sequential pruning strategy of select bonds in this model is then devised and implemented that enables engineering of specific mechanical behaviors upon deformation, both in the linear and in the nonlinear regimes. In particular, it is shown that Poisson's ratio can be tuned to arbitrary values. The model and concepts discussed here are validated by preparing physical realizations of the networks designed in this manner, which are produced by laser cutting 2D sheets and are found to behave as predicted. Furthermore, by relying on optimization algorithms, we exploit the networks' susceptibility to tuning to design networks that possess a distribution of stiffer and more compliant bonds and whose auxetic behavior is even greater than that of homogeneous networks. Taken together, the findings reported here serve to establish that pruned networks represent a promising platform for the creation of unique mechanical metamaterials.

  4. Self-assembled nanostructured metamaterials

    Science.gov (United States)

    Ponsinet, Virginie; Baron, Alexandre; Pouget, Emilie; Okazaki, Yutaka; Oda, Reiko; Barois, Philippe

    2017-07-01

    The concept of metamaterials emerged in the years 2000 with the achievement of artificial structures enabling nonconventional propagation of electromagnetic waves, such as negative phase velocity or negative refraction. The electromagnetic response of metamaterials is generally based on the presence of optically resonant elements —or meta-atoms— of sub-wavelength size and well-designed morphology so as to provide the desired electric and magnetic optical properties. Top-down technologies based on lithography techniques have been intensively used to fabricate a variety of efficient electric and magnetic resonators operating from microwave to visible light frequencies. However, the technological limits of the top-down approach are reached in visible light where a huge number of nanometre-sized elements is required. We show here that the bottom-up fabrication route based on the combination of nanochemistry and the self-assembly methods of colloidal physics provide an excellent alternative for the large-scale synthesis of complex meta-atoms, as well as for the fabrication of 2D and 3D samples exhibiting meta-properties in visible light. Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

  5. Photoconductive metamaterials with giant plasmonic photogalvanic effect

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Babicheva, Viktoriia; Evlyuknin, Andrey B.

    2014-01-01

    Photoelectric properties of metamaterials comprising oriented noncentrosymmetric metallic nanoparticle arrays in a homogeneous semiconductor matrix are theoretically studied. When uniformly illuminated by a plane wave, the asymmetric shape of the nanoparticles results in electro-motive force...

  6. Acoustic wave science realized by metamaterials.

    Science.gov (United States)

    Lee, Dongwoo; Nguyen, Duc Minh; Rho, Junsuk

    2017-01-01

    Artificially structured materials with unit cells at sub-wavelength scale, known as metamaterials, have been widely used to precisely control and manipulate waves thanks to their unconventional properties which cannot be found in nature. In fact, the field of acoustic metamaterials has been much developed over the past 15 years and still keeps developing. Here, we present a topical review of metamaterials in acoustic wave science. Particular attention is given to fundamental principles of acoustic metamaterials for realizing the extraordinary acoustic properties such as negative, near-zero and approaching-infinity parameters. Realization of acoustic cloaking phenomenon which is invisible from incident sound waves is also introduced by various approaches. Finally, acoustic lenses are discussed not only for sub-diffraction imaging but also for applications based on gradient index (GRIN) lens.

  7. Multifrequency Printed Antennas Loaded with Metamaterial Particles

    Directory of Open Access Journals (Sweden)

    D. Segovia-Vargas

    2009-06-01

    Full Text Available This paper provides a review of printed antennas loaded with metamaterial particles. This novel technique allows developing printed antennas with interesting features such as multifrequency (simultaneous operation over two or more frequency bands and multifunctionality (e. g. radiation pattern diversity. Moreover, compactness is also achieved and the main advantages of conventional printed antennas (light weight, low profile, low cost ... are maintained. Different types of metamaterial-loaded printed antennas are reviewed: printed dipoles and patch antennas. Several prototypes are designed, manufactured and measured showing good results. Furthermore, simple but accurate equivalent models are proposed. These models allow an easy and quick design of metamaterial-loaded printed antennas. Finally, two interesting applications based on the proposed antennas are reviewed: the patch antennas are used as radiating elements of emerging active RFID systems in the microwave band and the metamaterial-loaded printed dipoles are employed to increase the performance of log-periodic arrays.

  8. Hyperbolic metamaterial lens with hydrodynamic nonlocal response

    DEFF Research Database (Denmark)

    Yan, Wei; Mortensen, N. Asger; Wubs, Martijn

    2013-01-01

    We investigate the effects of hydrodynamic nonlocal response in hyperbolic metamaterials (HMMs), focusing on the experimentally realizable parameter regime where unit cells are much smaller than an optical wavelength but much larger than the wavelengths of the longitudinal pressure waves of the f......We investigate the effects of hydrodynamic nonlocal response in hyperbolic metamaterials (HMMs), focusing on the experimentally realizable parameter regime where unit cells are much smaller than an optical wavelength but much larger than the wavelengths of the longitudinal pressure waves...... in the local-response approximation and in the hydrodynamic Drude model can differ considerably. In particular, the optimal frequency for imaging in the nonlocal theory is blueshifted with respect to that in the local theory. Thus, to detect whether nonlocal response is at work in a hyperbolic metamaterial, we...... propose to measure the near-field distribution of a hyperbolic metamaterial lens....

  9. Deployable Thermoelectric Metamaterial Energy Harvesting Monitoring System

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will combine a novel asynchronous monitoring system with the first-of-its-kind thermoelectric metamaterial.  The thermoelectric prototype is constructed...

  10. Nonlocal Optical Response of Plasmonic Nanowire Metamaterials

    Science.gov (United States)

    2014-01-01

    can be expressed as the product = ()()(). Making this substitution, the differential equation can then be written as 1 ...nanowire geometry and solution method. 61 52 Transmission and reflection of the nanowire metamaterial are now compared for full- vectorial

  11. Metamaterials and Metasurfaces in THz Applications

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Malureanu, Radu; Zalkovskij, Maksim

    We present a set of terahertz optical components, such as linear and circular polarizers, absorbers, devices with enhanced transmittance, and single layer chiral systems based on metamaterials. Discussion covers design rules, fabrication and characterization.......We present a set of terahertz optical components, such as linear and circular polarizers, absorbers, devices with enhanced transmittance, and single layer chiral systems based on metamaterials. Discussion covers design rules, fabrication and characterization....

  12. Soil moisture sensors based on metamaterials

    Directory of Open Access Journals (Sweden)

    Goran Kitić

    2012-12-01

    Full Text Available In this paper novel miniature metamaterial-based soil moisture sensors are presented. The sensors are based on resonant-type metamaterials and employ split-ring resonators (SRR, spiral resonators and fractal SRRs to achieve small dimensions, high sensitivity, and compatibility with standard planar fabrication technologies. All these features make the proposedsensors suitable for deployment in agriculture for precise mapping of soil humidity.

  13. Wave propagation retrieval method for chiral metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Lavrinenko, Andrei

    2010-01-01

    In this paper we present the wave propagation method for the retrieving of effective properties of media with circularly polarized eigenwaves, in particularly for chiral metamaterials. The method is applied for thick slabs and provides bulk effective parameters. Its strong sides are the absence...... of artificial branches of the refractive index and simplicity in implementation. We prove the validity of the method on three case studies of homogeneous magnetized plasma, bi-cross and U-shaped metamaterials....

  14. Penetration effect in uniaxial anisotropic metamaterials

    Science.gov (United States)

    Vytovtov, K.; Barabanova, E.; Zouhdi, S.

    2018-02-01

    Plane harmonic wave propagation along an interface between vacuum and a semi-infinite anisotropic metamaterial is considered. Possibility of penetration effect in the considered case is studied. It is shown that there is a bulk wave within the anisotropic metamaterial with an arbitrary orientation of the anisotropy axis. It is also proved that a reflected wave must propagate perpendicularly to the interface in the case of the extraordinary wave. Moreover, no wave is reflected in the case of ordinary wave propagation.

  15. Active plasmonics and tuneable plasmonic metamaterials

    CERN Document Server

    Zayats, Anatoly V

    2013-01-01

    This book, edited by two of the most respected researchers in plasmonics,  gives an overview of the current state in plasmonics and plasmonic-based metamaterials, with an emphasis on active functionalities and an eye to future developments. This book is multifunctional, useful for newcomers and scientists interested in applications of plasmonics and metamaterials as well as for established researchers in this multidisciplinary area.

  16. Hybrid Metamaterials for Solar Biofuel Generation

    Science.gov (United States)

    2014-10-30

    AFRL-OSR-VA-TR-2014-0302 HYBRID METAMATERIALS FOR SOLAR BIOFUEL GENERATION Ronald Koder RESEARCH FOUNDATION OF THE CITY UNIVERSITY OF NEW YORK Final...administrative actions on them for him not sending a final report. Title: Hybrid metamaterials for solar biofuel generation Ronald L. Koder, Ph.D...novel multifunctional solar biofuel generating platform by coupling designed protein charge separation constructs with newly developed photonic

  17. Three-dimensional broadband tunable terahertz metamaterials

    DEFF Research Database (Denmark)

    Fan, Kebin; Strikwerda, Andrew; Zhang, Xin

    2013-01-01

    We present optically tunable magnetic three-dimensional (3D) metamaterials at terahertz (THz) frequencies which exhibit a tuning range of ~30% of the resonance frequency. This is accomplished by fabricating 3D array structures consisting of double-split-ring resonators (DSRRs) on silicon on sapph...... as verified through electromagnetic simulations and parameter retrieval. Our approach extends dynamic metamaterial tuning to magnetic control, and may find applications in switching and modulation, polarization control, or tunable perfect absorbers....

  18. Negative inductance circuits for metamaterial bandwidth enhancement

    Science.gov (United States)

    Avignon-Meseldzija, Emilie; Lepetit, Thomas; Ferreira, Pietro Maris; Boust, Fabrice

    2017-12-01

    Passive metamaterials have yet to be translated into applications on a large scale due in large part to their limited bandwidth. To overcome this limitation many authors have suggested coupling metamaterials to non-Foster circuits. However, up to now, the number of convincing demonstrations based on non-Foster metamaterials has been very limited. This paper intends to clarify why progress has been so slow, i.e., the fundamental difficulty in making a truly broadband and efficient non-Foster metamaterial. To this end, we consider two families of metamaterials, namely Artificial Magnetic Media and Artificial Magnetic Conductors. In both cases, it turns out that bandwidth enhancement requires negative inductance with almost zero resistance. To estimate bandwidth enhancement with actual non-Foster circuits, we consider two classes of such circuits, namely Linvill and gyrator. The issue of stability being critical, both metamaterial families are studied with equivalent circuits that include advanced models of these non-Foster circuits. Conclusions are different for Artificial Magnetic Media coupled to Linvill circuits and Artificial Magnetic Conductors coupled to gyrator circuits. In the first case, requirements for bandwidth enhancement and stability are very hard to meet simultaneously whereas, in the second case, an adjustment of the transistor gain does significantly increase bandwidth.

  19. A sound future for acoustic metamaterials.

    Science.gov (United States)

    Cummer, Steven

    2017-05-01

    The field of acoustic metamaterials borrowed ideas from electromagnetics and optics to create engineered structures that exhibit desired fluid or fluid-like properties for the propagation of sound. These metamaterials offer the possibility of manipulating and controlling sound waves in ways that are challenging or impossible with conventional materials. Metamaterials with zero, or negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales. The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. And active acoustic metamaterials use external control and power to create effective material properties that are fundamentally not possible with passive structures. Challenges remain, including the development of efficient techniques for fabricating large-scale metamaterial structures and, critically, converting exciting laboratory experiments into practically useful devices. In this presentation, I will outline the recent history of the field, describe some of the designs and properties of materials with unusual acoustic parameters, discuss examples of extreme manipulation of sound, and finally, provide a personal perspective on future directions in the field.

  20. Implementing Quantum Search Algorithm with Metamaterials.

    Science.gov (United States)

    Zhang, Weixuan; Cheng, Kaiyang; Wu, Chao; Wang, Yi; Li, Hongqiang; Zhang, Xiangdong

    2018-01-01

    Metamaterials, artificially structured electromagnetic (EM) materials, have enabled the realization of many unconventional EM properties not found in nature, such as negative refractive index, magnetic response, invisibility cloaking, and so on. Based on these man-made materials with novel EM properties, various devices are designed and realized. However, quantum analog devices based on metamaterials have not been achieved so far. Here, metamaterials are designed and printed to perform quantum search algorithm. The structures, comprising of an array of 2D subwavelength air holes with different radii perforated on the dielectric layer, are fabricated using a 3D-printing technique. When an incident wave enters in the designed metamaterials, the profile of beam wavefront is processed iteratively as it propagates through the metamaterial periodically. After ≈N roundtrips, precisely the same as the efficiency of quantum search algorithm, searched items will be found with the incident wave all focusing on the marked positions. Such a metamaterial-based quantum searching simulator may lead to remarkable achievements in wave-based signal processors. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Negative inductance circuits for metamaterial bandwidth enhancement

    Directory of Open Access Journals (Sweden)

    Avignon-Meseldzija Emilie

    2017-01-01

    Full Text Available Passive metamaterials have yet to be translated into applications on a large scale due in large part to their limited bandwidth. To overcome this limitation many authors have suggested coupling metamaterials to non-Foster circuits. However, up to now, the number of convincing demonstrations based on non-Foster metamaterials has been very limited. This paper intends to clarify why progress has been so slow, i.e., the fundamental difficulty in making a truly broadband and efficient non-Foster metamaterial. To this end, we consider two families of metamaterials, namely Artificial Magnetic Media and Artificial Magnetic Conductors. In both cases, it turns out that bandwidth enhancement requires negative inductance with almost zero resistance. To estimate bandwidth enhancement with actual non-Foster circuits, we consider two classes of such circuits, namely Linvill and gyrator. The issue of stability being critical, both metamaterial families are studied with equivalent circuits that include advanced models of these non-Foster circuits. Conclusions are different for Artificial Magnetic Media coupled to Linvill circuits and Artificial Magnetic Conductors coupled to gyrator circuits. In the first case, requirements for bandwidth enhancement and stability are very hard to meet simultaneously whereas, in the second case, an adjustment of the transistor gain does significantly increase bandwidth.

  2. Levitated crystals and quasicrystals of metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhehui [Los Alamos National Laboratory; Morris, Christopher [Los Alamos National Laboratory; Goree, John A [Dept Phys and Astron., University of Iowa

    2012-07-25

    New scientific and technological opportunities exist by marrying dusty plasma research with metamaterials. Specifically, by balancing control and self-assembly, certain laboratory plasmas can become a generic levitation platform for novel structure formation and nanomaterial synthesis. We propose to experimentally investigate two dimensional (2D) and three dimensional (3D) levitated structures of metamaterials and their properties. Such structures can self assemble in laboratory plasmas, similar to levitated dust crystals which were discovered in the mid 1990's. Laboratory plasma platform for metamaterial formation eliminates substrates upon which most metamaterials have to be supported. Three types of experiments, with similar setups, are discussed here. Levitated crystal structures of metamaterials using anisotropic microparticles are the most basic of the three. The second experiment examines whether quasicrystals of metamaterials are possible. Quasicrystals, discovered in the 1980's, possess so-called forbidden symmetries according to the conventional crystallography. The proposed experiment could answer many fundamental questions about structural, thermal and dynamical properties of quasicrystals. And finally, how to use nanoparticle coated microparticles to synthesize very long carbon nanotubes is also described. All of the experiments can fit inside a standard International Space Station locker with dimensions of 8-inch x 17-inch X 18-inch. Microgravity environment is deemed essential in particular for large 3D structures and very long carbon nanotube synthesis.

  3. Space-coiling metamaterials with double negativity and conical dispersion.

    Science.gov (United States)

    Liang, Zixian; Feng, Tianhua; Lok, Shukin; Liu, Fu; Ng, Kung Bo; Chan, Chi Hou; Wang, Jinjin; Han, Seunghoon; Lee, Sangyoon; Li, Jensen

    2013-01-01

    Metamaterials are effectively homogeneous materials that display extraordinary dispersion. Negative index metamaterials, zero index metamaterials and extremely anisotropic metamaterials are just a few examples. Instead of using locally resonating elements that may cause undesirable absorption, there are huge efforts to seek alternative routes to obtain these unusual properties. Here, we demonstrate an alternative approach for constructing metamaterials with extreme dispersion by simply coiling up space with curled channels. Such a geometric approach also has an advantage that the ratio between the wavelength and the lattice constant in achieving a negative or zero index can be changed in principle. It allows us to construct for the first time an acoustic metamaterial with conical dispersion, leading to a clear demonstration of negative refraction from an acoustic metamaterial with airborne sound. We also design and realize a double-negative metamaterial for microwaves under the same principle.

  4. Terahertz wave manipulation with metamaterials based on metal and graphene

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Zalkovskij, Maksim

    2013-01-01

    for active and passive materials and devices. Metamaterials, metal-dielectric artificial composites, propose wide possibilities for achieving unconventional electromagnetic properties, not found in nature. Moreover, metamaterials constructed of graphene, a monolayer of carbon atoms, allow for tunable...

  5. Transmission and reflection properties of terahertz fractal metamaterials

    DEFF Research Database (Denmark)

    Malureanu, Radu; Lavrinenko, Andrei; Cooke, David

    2010-01-01

    We use THz time-domain spectroscopy to investigate transmission and reflection properties of metallic fractal metamaterial structures. We observe loss of free-space energy at certain resonance frequencies, indicating excitation of surface modes of the metamaterial.......We use THz time-domain spectroscopy to investigate transmission and reflection properties of metallic fractal metamaterial structures. We observe loss of free-space energy at certain resonance frequencies, indicating excitation of surface modes of the metamaterial....

  6. Negative-index metamaterials: looking into the unit cell

    NARCIS (Netherlands)

    Burresi, M.; Diessel, D.; van Oosten, D.; Linden, Stefan; Wegener, M.; Kuipers, L.

    2010-01-01

    With their potential for spectacular applications, like superlensing and cloaking, metamaterials are a powerful class of nanostructured materials. All these applications rely on the metamaterials acting as a homogeneous material. We investigate a negative index metamaterial with a phase-sensitive

  7. Topology Optimization of Metamaterial-Based Electrically Small Antennas

    DEFF Research Database (Denmark)

    Erentok, Aycan; Sigmund, Ole

    2007-01-01

    A topology optimized metamaterial-based electrically small antenna configuration that is independent of a specific spherical and/or cylindrical metamaterial shell design is demonstrated. Topology optimization is shown to provide the optimal value and placement of a given ideal metamaterial in space...

  8. Metamaterials with magnetism and chirality

    Science.gov (United States)

    Tomita, Satoshi; Kurosawa, Hiroyuki; Ueda, Tetsuya; Sawada, Kei

    2018-02-01

    This review introduces and overviews electromagnetism in structured metamaterials which undergo simultaneous time-reversal and space-inversion symmetry breaking due to magnetism and chirality. Direct experimental observation of optical magnetochiral effects in a single metamolecule with magnetism and chirality is demonstrated at microwave frequencies. Numerical simulations based on a finite element method reproduce the experimental results well, and predict the emergence of giant magnetochiral effects, by combining resonances in the metamolecule. Toward the realization of magnetochiral effects at higher frequencies than microwaves, a metamolecule is miniaturized in the presence of ferromagnetic resonance in a cavity and coplanar waveguide. This work opens the door to the realization of a one-way mirror and synthetic gauge fields for electromagnetic waves.

  9. Auxetic metamaterials from disordered networks

    Science.gov (United States)

    Reid, Daniel R.; Pashine, Nidhi; Wozniak, Justin M.; Jaeger, Heinrich M.; Liu, Andrea J.; Nagel, Sidney R.; de Pablo, Juan J.

    2018-02-01

    Recent theoretical work suggests that systematic pruning of disordered networks consisting of nodes connected by springs can lead to materials that exhibit a host of unusual mechanical properties. In particular, global properties such as Poisson’s ratio or local responses related to deformation can be precisely altered. Tunable mechanical responses would be useful in areas ranging from impact mitigation to robotics and, more generally, for creation of metamaterials with engineered properties. However, experimental attempts to create auxetic materials based on pruning-based theoretical ideas have not been successful. Here we introduce a more realistic model of the networks, which incorporates angle-bending forces and the appropriate experimental boundary conditions. A sequential pruning strategy of select bonds in this model is then devised and implemented that enables engineering of specific mechanical behaviors upon deformation, both in the linear and in the nonlinear regimes. In particular, it is shown that Poisson’s ratio can be tuned to arbitrary values. The model and concepts discussed here are validated by preparing physical realizations of the networks designed in this manner, which are produced by laser cutting 2D sheets and are found to behave as predicted. Furthermore, by relying on optimization algorithms, we exploit the networks’ susceptibility to tuning to design networks that possess a distribution of stiffer and more compliant bonds and whose auxetic behavior is even greater than that of homogeneous networks. Taken together, the findings reported here serve to establish that pruned networks represent a promising platform for the creation of unique mechanical metamaterials.

  10. Retrieval of high-order susceptibilities of nonlinear metamaterials

    International Nuclear Information System (INIS)

    Wang Zhi-Yu; Qiu Jin-Peng; Chen Hua; Mo Jiong-Jiong; Yu Fa-Xin

    2017-01-01

    Active metamaterials embedded with nonlinear elements are able to exhibit strong nonlinearity in microwave regime. However, existing S -parameter based parameter retrieval approaches developed for linear metamaterials do not apply in nonlinear cases. In this paper, a retrieval algorithm of high-order susceptibilities for nonlinear metamaterials is derived. Experimental demonstration shows that, by measuring the power level of each harmonic while sweeping the incident power, high-order susceptibilities of a thin-layer nonlinear metamaterial can be effectively retrieved. The proposedapproach can be widely used in the research of active metamaterials. (paper)

  11. Surface waves guided by metamaterials with rotational disorder

    Science.gov (United States)

    Gric, T.; Hess, O.

    2018-02-01

    The analytical analysis of the metamaterial boundary with the rotational disorder reveals both bound and leaky surface plasmon (SP) modes. The dispersion relations of SPs propagating on a surface of these metamaterials are presented along with the propagation lengths. The rigorous modeling and analysis of surface waves at the boundary of two metamaterials possessing rotational disorder are presented. Dispersion properties of two different metamaterial boundaries have been investigated. The results show that the boundary of the metamaterials having different dielectrics employed allows for the presence of the particular modes crossing the light line with the significant portion at lower frequencies lying above the free space light line.

  12. Tunable reflecting terahertz filter based on chirped metamaterial structure

    Science.gov (United States)

    Yang, Jing; Gong, Cheng; Sun, Lu; Chen, Ping; Lin, Lie; Liu, Weiwei

    2016-01-01

    Tunable reflecting terahertz bandstop filter based on chirped metamaterial structure is demonstrated by numerical simulation. In the metamaterial, the metal bars are concatenated to silicon bars with different lengths. By varying the conductivity of the silicon bars, the reflectivity, central frequency and bandwidth of the metamaterial could be tuned. Light illumination could be introduced to change the conductivity of the silicon bars. Numerical simulations also show that the chirped metamaterial structure is insensitive to the incident angle and polarization-dependent. The proposed chirped metamaterial structure can be operated as a tunable bandstop filter whose modulation depth, bandwidth, shape factor and center frequency can be controlled by light pumping. PMID:27941833

  13. Synthesis of C-linked carbo-β2-amino acids and β2-peptides: design of new motifs for left-handed 12/10- and 10/12-mixed helices.

    Science.gov (United States)

    Sharma, Gangavaram V M; Reddy, Nelli Yella; Ravi, Rapolu; Sreenivas, Bommagani; Sridhar, Gattu; Chatterjee, Deepak; Kunwar, Ajit C; Hofmann, Hans-Jörg

    2012-12-14

    C-linked carbo-β(2)-amino acids (β(2)-Caa), a new class of β-amino acid with a carbohydrate side chain having d-xylo configuration, were prepared from d-glucose. The main idea behind the design of the new β-amino acids was to move the steric strain of the bulky carbohydrate side chain from the Cβ- to the Cα-carbon atom and to explore its influence on the folding propensities in peptides with alternating (R)- and (S)-β(2)-Caas. The tetra- and hexapeptides derived were studied employing NMR (in CDCl(3)), CD, and molecular dynamics simulations. The β(2)-peptides of the present study form left-handed 12/10- and 10/12-mixed helices independent of the order of the alternating chiral amino acids in the sequence and result in a new motif. These results differ from earlier findings on β(3)-peptides of the same design, containing a carbohydrate side chain with d-xylo configuration, which form exclusively right-handed 12/10-mixed helices. Quantum chemical calculations employing ab initio MO theory suggest the side chain chirality as an important factor for the observed definite left- or right-handedness of the helices in the β(2)- and β(3)-peptides.

  14. Plasma metamaterials as cloaking and nonlinear media

    Science.gov (United States)

    Sakai, O.; Yamaguchi, S.; Bambina, A.; Iwai, A.; Nakamura, Y.; Tamayama, Y.; Miyagi, S.

    2017-01-01

    Plasma metamaterials, composites of low-temperature plasmas and periodic functional microstructures, work as cloaking and nonlinear media. Due to functions of the microstructures like negative permeability, electromagnetic waves in and around plasma metamaterials propagate in a quite different manner from the case with the conventional space in which relative permeability is positive and unity. Using plasmas and plasma metamaterials, we achieve various controls of microwave propagating paths such as unidirectionality and cloaking in the two- or 3D spaces. For instance, a concentric plasma layer makes wave propagation unidirectional, and waves propagate in different routes when they start inside or outside the concentric layer. Furthermore, due to spatial permittivity gradient and anisotropic refractive index, electromagnetic waves detour in plasma metamaterial layers. Another significant point that plasma metamaterials can realize is nonlinearity. When we study high-power electromagnetic waves propagating in them, we observe several properties describable in terms of nonlinear dynamics and nonlinear photonics. Microwaves beyond threshold energy trigger bifurcations in plasma permittivity, and the second harmonic wave detected simultaneously is generated with strong emission levels. Such electromagnetic wave propagation is achieved with advantages over other materials, since plasmas and metallic microstructures work in harmony and in synergy.

  15. V-band electronically reconfigurable metamaterial

    Science.gov (United States)

    Radisic, Vesna; Hester, Jimmy G.; Nguyen, Vinh N.; Caira, Nicholas W.; DiMarzio, Donald; Hilgeman, Theodore; Larouche, Stéphane; Kaneshiro, Eric; Gutierrez-Aitken, Augusto

    2017-04-01

    In this work, we report on a reconfigurable V-band metamaterial fabricated using an InP heterojunction bipolar transistor production process. As designed and fabricated, the implementation uses complementary split ring resonators (cSRRs) and Schottky diodes in both single unit cell and three unit cell monolithic microwave integrated circuits. Each unit cell has two diodes embedded within the gaps of the cSRRs. Reconfigurability is achieved by applying an external bias that turns the diodes on and off, which effectively controls the resonant property of the structure. In order to measure the metamaterial properties, the unit cells are fed and followed by transmission lines. Measured data show good agreement with simulations and demonstrate that the metamaterial structure exhibits resonance at around 65 GHz that can be switched on and off. The three-unit cell transmission line metamaterial shows a deeper resonance and a larger phase change than a single cell, as expected. These are the first reported reconfigurable metamaterials operating at the V-band using the InP high speed device fabrication process.

  16. Advances in active and nonlinear metamaterials

    Science.gov (United States)

    Boardman, A. D.; Mitchell-Thomas, R. C.; Rapoport, Y. G.

    2012-09-01

    Metamaterial research is an extremely important global activity that promises to change our lives in many different ways. These include making objects invisible and the dramatic impact of metamaterials upon the energy and medical sectors of society. Behind all of the applications, however, lies the business of creating metamaterials that are not going to be crippled by the kind of loss that is naturally heralded by use of resonant responses in their construction. Under the general heading of active and tunable metamaterials, an elegant route to the inclusion of nonlinearity and waveguide complexity coupled to soliton behavior suggested by forms of transformation dynamics is presented. In addition, various discussions will be framed within a magnetooptical environment that deploys externally applied magnetic field orientations. Light can then be directed to achieve energy control and be deployed for a variety of outcomes. Quite apart from the fact that the manufacture of metamaterials is attracting such a lot of global attention, the ability to control light, for example, in these materials is also immensely interesting and will lead to a new dawn of integrated circuits and computers. Recognizing the role of nonlinearity raises the possibility that dramatic manufacturing and applications are on the horizon.

  17. Programmable Self-Locking Origami Mechanical Metamaterials.

    Science.gov (United States)

    Fang, Hongbin; Chu, Shih-Cheng A; Xia, Yutong; Wang, Kon-Well

    2018-03-07

    Developing mechanical metamaterials with programmable properties is an emerging topic receiving wide attention. While the programmability mainly originates from structural multistability in previously designed metamaterials, here it is shown that nonflat-foldable origami provides a new platform to achieve programmability via its intrinsic self-locking and reconfiguration capabilities. Working with the single-collinear degree-4 vertex origami tessellation, it is found that each unit cell can self-lock at a nonflat configuration and, therefore, possesses wide design space to program its foldability and relative density. Experiments and numerical analyses are combined to demonstrate that by switching the deformation modes of the constituent cell from prelocking folding to postlocking pressing, its stiffness experiences a sudden jump, implying a limiting-stopper effect. Such a stiffness jump is generalized to a multisegment piecewise stiffness profile in a multilayer model. Furthermore, it is revealed that via strategically switching the constituent cells' deformation modes through passive or active means, the n-layer metamaterial's stiffness is controllable among 2 n target stiffness values. Additionally, the piecewise stiffness can also trigger bistable responses dynamically under harmonic excitations, highlighting the metamaterial's rich dynamic performance. These unique characteristics of self-locking origami present new paths for creating programmable mechanical metamaterials with in situ controllable mechanical properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Acoustic metamaterials: From local resonances to broad horizons.

    Science.gov (United States)

    Ma, Guancong; Sheng, Ping

    2016-02-01

    Within a time span of 15 years, acoustic metamaterials have emerged from academic curiosity to become an active field driven by scientific discoveries and diverse application potentials. This review traces the development of acoustic metamaterials from the initial findings of mass density and bulk modulus frequency dispersions in locally resonant structures to the diverse functionalities afforded by the perspective of negative constitutive parameter values, and their implications for acoustic wave behaviors. We survey the more recent developments, which include compact phase manipulation structures, superabsorption, and actively controllable metamaterials as well as the new directions on acoustic wave transport in moving fluid, elastic, and mechanical metamaterials, graphene-inspired metamaterials, and structures whose characteristics are best delineated by non-Hermitian Hamiltonians. Many of the novel acoustic metamaterial structures have transcended the original definition of metamaterials as arising from the collective manifestations of constituent resonating units, but they continue to extend wave manipulation functionalities beyond those found in nature.

  19. Shape-matching soft mechanical metamaterials.

    Science.gov (United States)

    Mirzaali, M J; Janbaz, S; Strano, M; Vergani, L; Zadpoor, A A

    2018-01-17

    Architectured materials with rationally designed geometries could be used to create mechanical metamaterials with unprecedented or rare properties and functionalities. Here, we introduce "shape-matching" metamaterials where the geometry of cellular structures comprising auxetic and conventional unit cells is designed so as to achieve a pre-defined shape upon deformation. We used computational models to forward-map the space of planar shapes to the space of geometrical designs. The validity of the underlying computational models was first demonstrated by comparing their predictions with experimental observations on specimens fabricated with indirect additive manufacturing. The forward-maps were then used to devise the geometry of cellular structures that approximate the arbitrary shapes described by random Fourier's series. Finally, we show that the presented metamaterials could match the contours of three real objects including a scapula model, a pumpkin, and a Delft Blue pottery piece. Shape-matching materials have potential applications in soft robotics and wearable (medical) devices.

  20. Contemporary optoelectronics materials, metamaterials and device applications

    CERN Document Server

    Sukhoivanov, Igor

    2016-01-01

    This book presents a collection of extended contributions on the physics and application of optoelectronic materials and metamaterials.   The book is divided into three parts, respectively covering materials, metamaterials and optoelectronic devices.  Individual chapters cover topics including phonon-polariton interaction, semiconductor and nonlinear organic materials, metallic, dielectric and gyrotropic metamaterials, singular optics, parity-time symmetry, nonlinear plasmonics, microstructured optical fibers, passive nonlinear shaping of ultrashort pulses, and pulse-preserving supercontinuum generation. The book contains both experimental and theoretical studies, and each contribution is a self-contained exposition of a particular topic, featuring an extensive reference list.  The book will be a useful resource for graduate and postgraduate students, researchers and engineers involved in optoelectronics/photonics, quantum electronics, optics, and adjacent areas of science and technology.

  1. Optical magnetic response from parallel plate metamaterials

    Science.gov (United States)

    Huang, Zhiming; Xue, Jianqiang; Hou, Yun; Chu, Junhao; Zhang, D. H.

    2006-11-01

    We propose a metamaterial with a three-layer structure based on Faraday’s law. The metamaterial is simply formed by a pair of homogeneous parallel plates separated by a thin medium. We also propose a virtual current loop with length of 2a ( a is the attenuation constant) in the plates, which can be formed upon excitation of an electromagnetic field. Strong magnetic response has been observed by spectroscopic ellipsometry and the resonant frequency can be widely tuned by varying the structure dimensions. The observations are also verified by optical transfer matrix. The easy fabrication and high interfacial quality of the structure will make the applications of the magnetic response and negative refractive index metamaterials a reality.

  2. Broadband plasmon induced transparency in terahertz metamaterials

    KAUST Repository

    Zhu, Zhihua

    2013-04-25

    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. © 2013 IOP Publishing Ltd.

  3. PURCELL EFFECT IN EXTREMELY ANISOTROPIC ELLIPTIC METAMATERIALS

    Directory of Open Access Journals (Sweden)

    Alexander V. Chebykin

    2014-11-01

    Full Text Available The paper deals with theoretical demonstration of Purcell effect in extremely anisotropic metamaterials with elliptical isofrequency surface. This effect is free from association with divergence in density of states unlike the case of hyperbolic metamaterials. It is shown that a large Purcell factor can be observed without excitation of modes with large wave vectors in one direction, and the component of the wave vector normal to the layers is less than k0. For these materials the possibility is given for increasing of the power radiated in the medium, as well as the power radiated from material into free space across the medium border situated transversely to the layers. We have investigated isofrequency contours and the dependence of Purcell factor from the frequency for infinite layered metamaterial structure. In the visible light range strong spatial dispersion gives no possibility to obtain enhancement of spontaneous emission in metamaterial with unit cell which consists of two layers. This effect can be achieved in periodic metal-dielectric layered nanostructures with a unit cell containing two different metallic layers and two dielectric ones. Analysis of the dependences for Purcell factor from the frequency shows that the spontaneous emission is enhanced by a factor of ten or more only for dipole orientation along metamaterial layers, but in the case of the transverse orientation radiation can be enhanced only 2-3 times at most. The results can be used to create a new type of metamaterials with elliptical isofrequency contours, providing a more efficient light emission in the far field.

  4. Negative stiffness honeycombs as tunable elastic metamaterials

    Science.gov (United States)

    Goldsberry, Benjamin M.; Haberman, Michael R.

    2018-03-01

    Acoustic and elastic metamaterials are media with a subwavelength structure that behave as effective materials displaying atypical effective dynamic properties. These material systems are of interest because the design of their sub-wavelength structure allows for direct control of macroscopic wave dispersion. One major design limitation of most metamaterial structures is that the dynamic response cannot be altered once the microstructure is manufactured. However, the ability to modify wave propagation in the metamaterial with an external stimulus is highly desirable for numerous applications and therefore remains a significant challenge in elastic metamaterials research. In this work, a honeycomb structure composed of a doubly periodic array of curved beams, known as a negative stiffness honeycomb (NSH), is analyzed as a tunable elastic metamaterial. The nonlinear static elastic response that results from large deformations of the NSH unit cell leads to a large variation in linear elastic wave dispersion associated with infinitesimal motion superposed on the externally imposed pre-strain. A finite element model is utilized to model the static deformation and subsequent linear wave motion at the pre-strained state. Analysis of the slowness surface and group velocity demonstrates that the NSH exhibits significant tunability and a high degree of anisotropy which can be used to guide wave energy depending on static pre-strain levels. In addition, it is shown that partial band gaps exist where only longitudinal waves propagate. The NSH therefore behaves as a meta-fluid, or pentamode metamaterial, which may be of use for applications of transformation elastodynamics such as cloaking and gradient index lens devices.

  5. Summary of ongoing TARDEC Work in Metamaterials Relevant to NATO SET-181

    Science.gov (United States)

    2013-08-21

    Meitzler, T., Bankowski, E., Tiberkevich, T., and Slavin, A., Book Chapter on Spin-Torque Microwave Detectors, Magnonics - From Fundamentals to...harvesting - spintronic metamaterials; Non-reciprocity without magnetic field – magnonic metamaterials; Stealth and cloaking – optical metamaterials.

  6. Large scale phononic metamaterials for seismic isolation

    Energy Technology Data Exchange (ETDEWEB)

    Aravantinos-Zafiris, N. [Department of Sound and Musical Instruments Technology, Ionian Islands Technological Educational Institute, Stylianou Typaldou ave., Lixouri 28200 (Greece); Sigalas, M. M. [Department of Materials Science, University of Patras, Patras 26504 (Greece)

    2015-08-14

    In this work, we numerically examine structures that could be characterized as large scale phononic metamaterials. These novel structures could have band gaps in the frequency spectrum of seismic waves when their dimensions are chosen appropriately, thus raising the belief that they could be serious candidates for seismic isolation structures. Different and easy to fabricate structures were examined made from construction materials such as concrete and steel. The well-known finite difference time domain method is used in our calculations in order to calculate the band structures of the proposed metamaterials.

  7. Metamaterials modelling, fabrication, and characterisation techniques

    DEFF Research Database (Denmark)

    Malureanu, Radu; Zalkovskij, Maksim; Andryieuski, Andrei

    2012-01-01

    Metamaterials are artificially designed media that show averaged properties not yet encountered in nature. Among such properties, the possibility of obtaining optical magnetism and negative refraction are the ones mainly exploited but epsilon-near-zero and sub-unitary refraction index are also...... parameters that can be obtained. Such behaviour enables unprecedented applications. Within this work, we will present various aspects of metamaterials research field that we deal with at our department. From the modelling part, we will present tour approach for determining the field enhancement in slits...

  8. Metamaterials modelling, fabrication and characterisation techniques

    DEFF Research Database (Denmark)

    Malureanu, Radu; Zalkovskij, Maksim; Andryieuski, Andrei

    Metamaterials are artificially designed media that show averaged properties not yet encountered in nature. Among such properties, the possibility of obtaining optical magnetism and negative refraction are the ones mainly exploited but epsilon-near-zero and sub-unitary refraction index are also...... parameters that can be obtained. Such behaviour enables unprecedented applications. Within this work, we will present various aspects of metamaterials research field that we deal with at our department. From the modelling part, various approaches for determining the value of the refractive index...

  9. A microsphere suspension model of metamaterial fluids

    Directory of Open Access Journals (Sweden)

    Qian Duan

    2017-05-01

    Full Text Available Drawing an analogy to the liquid phase of natural materials, we theoretically propose a microsphere suspension model to realize a metamaterial fluid with artificial electromagnetic indexes. By immersing high-ε, micrometer-sized dielectric spheres in a low-ε insulating oil, the structured fluid exhibits liquid-like properties from dispersing phase as well as the isotropic negative electromagnetic parameters caused by Mie resonances from dispersed microspheres. The work presented here will benefit the development of structured fluids toward metamaterials.

  10. Graphene and Graphene Metamaterials for Terahertz Absorbers

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim

    2013-01-01

    Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows...... for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present our recent experimental results on the graphene absorbers characterization....

  11. Large scale phononic metamaterials for seismic isolation

    International Nuclear Information System (INIS)

    Aravantinos-Zafiris, N.; Sigalas, M. M.

    2015-01-01

    In this work, we numerically examine structures that could be characterized as large scale phononic metamaterials. These novel structures could have band gaps in the frequency spectrum of seismic waves when their dimensions are chosen appropriately, thus raising the belief that they could be serious candidates for seismic isolation structures. Different and easy to fabricate structures were examined made from construction materials such as concrete and steel. The well-known finite difference time domain method is used in our calculations in order to calculate the band structures of the proposed metamaterials

  12. Bistability in mushroom-type metamaterials

    Science.gov (United States)

    Fernandes, David E.; Silveirinha, Mário G.

    2017-07-01

    Here, we study the electromagnetic response of asymmetric mushroom-type metamaterials loaded with nonlinear elements. It is shown that near a Fano resonance, these structures may have a strong tunable, bistable, and switchable response and enable giant nonlinear effects. By using an effective medium theory and full wave simulations, it is proven that the nonlinear elements may allow the reflection and transmission coefficients to follow hysteresis loops, and to switch the metamaterial between "go" and "no-go" states similar to an ideal electromagnetic switch.

  13. Magnetic nanoparticles for tunable microwave metamaterials

    KAUST Repository

    Noginova, Natalia

    2012-09-24

    Commonly, metamaterials are electrically engineered systems with optimized spatial arrangement of subwavelength sized metal and dielectric components. We explore alternative methods based on use of magnetic inclusions, such as magnetic nanoparticles, which can allow permeability of a composite to be tuned from negative to positive at the range of magnetic resonance. To better understand effects of particle size and magnetization dynamics, we performed electron magnetic resonance study on several varieties of magnetic nanoparticles and determined potential of nanoparticle use as building blocks for tunable microwave metamaterials. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  14. Equivalent circuit analysis of terahertz metamaterial filters

    KAUST Repository

    Zhang, Xueqian

    2011-01-01

    An equivalent circuit model for the analysis and design of terahertz (THz) metamaterial filters is presented. The proposed model, derived based on LMC equivalent circuits, takes into account the detailed geometrical parameters and the presence of a dielectric substrate with the existing analytic expressions for self-inductance, mutual inductance, and capacitance. The model is in good agreement with the experimental measurements and full-wave simulations. Exploiting the circuit model has made it possible to predict accurately the resonance frequency of the proposed structures and thus, quick and accurate process of designing THz device from artificial metamaterials is offered. ©2011 Chinese Optics Letters.

  15. The Talbot effect in a metamaterial

    Science.gov (United States)

    Nikkhah, H.; Hasan, M.; Hall, T. J.

    2018-02-01

    The effect of anisotropy and spatial dispersion of a metamaterial on the Talbot effect may be engineered in principle. This has profound implications for applications of the Talbot effect such as the design of a multimode interference coupler (MMI). The paper describes how a metamaterial can suppress the modal phase error which otherwise limits the scaling of MMI port dimension. A binary multilayer dielectric material described by the Kronig-Penney model is shown to provide a close approximation to the required dispersion relation. Results of simulations of a multi-slotted waveguide MMI engineered to provide a polarising beam splitter function are given as an example of the method.

  16. Anisotropic dissipation in lattice metamaterials

    Directory of Open Access Journals (Sweden)

    Dimitri Krattiger

    2016-12-01

    Full Text Available Plane wave propagation in an elastic lattice material follows regular patterns as dictated by the nature of the lattice symmetry and the mechanical configuration of the unit cell. A unique feature pertains to the loss of elastodynamic isotropy at frequencies where the wavelength is on the order of the lattice spacing or shorter. Anisotropy may also be realized at lower frequencies with the inclusion of local resonators, especially when designed to exhibit directionally non-uniform connectivity and/or cross-sectional geometry. In this paper, we consider free and driven waves within a plate-like lattice−with and without local resonators−and examine the effects of damping on the isofrequency dispersion curves. We also examine, for free waves, the effects of damping on the frequency-dependent anisotropy of dissipation. Furthermore, we investigate the possibility of engineering the dissipation anisotropy by tuning the directional properties of the prescribed damping. The results demonstrate that uniformly applied damping tends to reduce the intensity of anisotropy in the isofrequency dispersion curves. On the other hand, lattice crystals and metamaterials are shown to provide an excellent platform for direction-dependent dissipation engineering which may be realized by simple changes in the spatial distribution of the damping elements.

  17. Metamaterial mirrors in optoelectronic devices

    KAUST Repository

    Esfandyarpour, Majid

    2014-06-22

    The phase reversal that occurs when light is reflected from a metallic mirror produces a standing wave with reduced intensity near the reflective surface. This effect is highly undesirable in optoelectronic devices that use metal films as both electrical contacts and optical mirrors, because it dictates a minimum spacing between the metal and the underlying active semiconductor layers, therefore posing a fundamental limit to the overall thickness of the device. Here, we show that this challenge can be circumvented by using a metamaterial mirror whose reflection phase is tunable from that of a perfect electric mirror († = €) to that of a perfect magnetic mirror († = 0). This tunability in reflection phase can also be exploited to optimize the standing wave profile in planar devices to maximize light-matter interaction. Specifically, we show that light absorption and photocurrent generation in a sub-100 nm active semiconductor layer of a model solar cell can be enhanced by ∼20% over a broad spectral band. © 2014 Macmillan Publishers Limited.

  18. Negative Refractive Index in Artificial Metamaterials

    OpenAIRE

    Grigorenko, A. N.

    2006-01-01

    We discuss optical constants in artificial metamaterials showing negative magnetic permeability and electric permittivity. Using effective field theory, we calculate effective permeability of nanofabricated media composed of pairs of identical gold nano-pillars with magnetic response in the visible spectrum.

  19. Engineering modes in optical fibers with metamaterial

    DEFF Research Database (Denmark)

    Yan, Min; Mortensen, Asger; Qiu, Min

    2009-01-01

    In this paper, we report a preliminary theoretical study on optical fibers with fine material inclusions whose geometrical inhomogeneity is almost indistinguishable by the operating wavelength.We refer to such fibers as metamaterial optical fibers, which can conceptually be considered as an exten...

  20. Laser Writing of Multiscale Chiral Polymer Metamaterials

    Directory of Open Access Journals (Sweden)

    E. P. Furlani

    2012-01-01

    Full Text Available A new approach to metamaterials is presented that involves laser-based patterning of novel chiral polymer media, wherein chirality is realized at two distinct length scales, intrinsically at the molecular level and geometrically at a length scale on the order of the wavelength of the incident field. In this approach, femtosecond-pulsed laser-induced two-photon lithography (TPL is used to pattern a photoresist-chiral polymer mixture into planar chiral shapes. Enhanced bulk chirality can be realized by tuning the wavelength-dependent chiral response at both the molecular and geometric level to ensure an overlap of their respective spectra. The approach is demonstrated via the fabrication of a metamaterial consisting of a two-dimensional array of chiral polymer-based L-structures. The fabrication process is described and modeling is performed to demonstrate the distinction between molecular and planar geometric-based chirality and the effects of the enhanced multiscale chirality on the optical response of such media. This new approach to metamaterials holds promise for the development of tunable, polymer-based optical metamaterials with low loss.

  1. Optical Metamaterials: Design, Characterization and Applications

    Science.gov (United States)

    Chaturvedi, Pratik

    2009-01-01

    Artificially engineered metamaterials have emerged with properties and functionalities previously unattainable in natural materials. The scientific breakthroughs made in this new class of electromagnetic materials are closely linked with progress in developing physics-driven design, novel fabrication and characterization methods. The intricate…

  2. Demixing light paths inside disordered metamaterials

    NARCIS (Netherlands)

    Vellekoop, Ivo Micha; van Putten, E.G.; Putten, E.G.; Lagendijk, Aart; Mosk, Allard

    2008-01-01

    We experimentally demonstrate the first method to focus light inside disordered photonic metamaterials. In such materials, scattering prevents light from forming a geometric focus. Instead of geometric optics, we used multi-path interference to make the scattering process itself concentrate light on

  3. Ultralight shape-recovering plate mechanical metamaterials.

    Science.gov (United States)

    Davami, Keivan; Zhao, Lin; Lu, Eric; Cortes, John; Lin, Chen; Lilley, Drew E; Purohit, Prashant K; Bargatin, Igor

    2015-12-03

    Unusual mechanical properties of mechanical metamaterials are determined by their carefully designed and tightly controlled geometry at the macro- or nanoscale. We introduce a class of nanoscale mechanical metamaterials created by forming continuous corrugated plates out of ultrathin films. Using a periodic three-dimensional architecture characteristic of mechanical metamaterials, we fabricate free-standing plates up to 2 cm in size out of aluminium oxide films as thin as 25 nm. The plates are formed by atomic layer deposition of ultrathin alumina films on a lithographically patterned silicon wafer, followed by complete removal of the silicon substrate. Unlike unpatterned ultrathin films, which tend to warp or even roll up because of residual stress gradients, our plate metamaterials can be engineered to be extremely flat. They weigh as little as 0.1 g cm(-2) and have the ability to 'pop-back' to their original shape without damage even after undergoing multiple sharp bends of more than 90°.

  4. Combinatorial design of textured mechanical metamaterials.

    Science.gov (United States)

    Coulais, Corentin; Teomy, Eial; de Reus, Koen; Shokef, Yair; van Hecke, Martin

    2016-07-28

    The structural complexity of metamaterials is limitless, but, in practice, most designs comprise periodic architectures that lead to materials with spatially homogeneous features. More advanced applications in soft robotics, prosthetics and wearable technology involve spatially textured mechanical functionality, which requires aperiodic architectures. However, a naive implementation of such structural complexity invariably leads to geometrical frustration (whereby local constraints cannot be satisfied everywhere), which prevents coherent operation and impedes functionality. Here we introduce a combinatorial strategy for the design of aperiodic, yet frustration-free, mechanical metamaterials that exhibit spatially textured functionalities. We implement this strategy using cubic building blocks-voxels-that deform anisotropically, a local stacking rule that allows cooperative shape changes by guaranteeing that deformed building blocks fit together as in a three-dimensional jigsaw puzzle, and three-dimensional printing. These aperiodic metamaterials exhibit long-range holographic order, whereby the two-dimensional pixelated surface texture dictates the three-dimensional interior voxel arrangement. They also act as programmable shape-shifters, morphing into spatially complex, but predictable and designable, shapes when uniaxially compressed. Finally, their mechanical response to compression by a textured surface reveals their ability to perform sensing and pattern analysis. Combinatorial design thus opens up a new avenue towards mechanical metamaterials with unusual order and machine-like functionalities.

  5. Characterization of nanodiamonds for metamaterial applications

    OpenAIRE

    Shalaginov, Mikhail; Naik, Gururaj; Ishii, Satoshi; Slipchenko, Mikhail; Boltasseva, Alexandra; Cheng, Ji-Xin; Smolyaninov, A N; Kochman, E; Shalaev, Vladimir

    2011-01-01

    Several different types of nanodiamonds were characterized in order to find the best sample to be used in further experiments with metamaterials. In this work we present the results of optical analysis of aqueous suspensions containing nanodiamonds, SEM analysis of diamond particles dispersed on silicon substrates and measurements of photoluminescence from defects in nanodiamonds.

  6. Metamaterial Model of Tachyonic Dark Energy

    Directory of Open Access Journals (Sweden)

    Igor I. Smolyaninov

    2014-02-01

    Full Text Available Dark energy with negative pressure and positive energy density is believed to be responsible for the accelerated expansion of the universe. Quite a few theoretical models of dark energy are based on tachyonic fields interacting with itself and normal (bradyonic matter. Here, we propose an experimental model of tachyonic dark energy based on hyperbolic metamaterials. Wave equation describing propagation of extraordinary light inside hyperbolic metamaterials exhibits 2 + 1 dimensional Lorentz symmetry. The role of time in the corresponding effective 3D Minkowski spacetime is played by the spatial coordinate aligned with the optical axis of the metamaterial. Nonlinear optical Kerr effect bends this spacetime resulting in effective gravitational force between extraordinary photons. We demonstrate that this model has a self-interacting tachyonic sector having negative effective pressure and positive effective energy density. Moreover, a composite multilayer SiC-Si hyperbolic metamaterial exhibits closely separated tachyonic and bradyonic sectors in the long wavelength infrared range. This system may be used as a laboratory model of inflation and late time acceleration of the universe.

  7. Optical magnetism in planar metamaterial heterostructures.

    Science.gov (United States)

    Papadakis, Georgia T; Fleischman, Dagny; Davoyan, Artur; Yeh, Pochi; Atwater, Harry A

    2018-01-18

    Harnessing artificial optical magnetism has previously required complex two- and three-dimensional structures, such as nanoparticle arrays and split-ring metamaterials. By contrast, planar structures, and in particular dielectric/metal multilayer metamaterials, have been generally considered non-magnetic. Although the hyperbolic and plasmonic properties of these systems have been extensively investigated, their assumed non-magnetic response limits their performance to transverse magnetic (TM) polarization. We propose and experimentally validate a mechanism for artificial magnetism in planar multilayer metamaterials. We also demonstrate that the magnetic properties of high-index dielectric/metal hyperbolic metamaterials can be anisotropic, leading to magnetic hyperbolic dispersion in certain frequency regimes. We show that such systems can support transverse electric polarized interface-bound waves, analogous to their TM counterparts, surface plasmon polaritons. Our results open a route for tailoring optical artificial magnetism in lithography-free layered systems and enable us to generalize the plasmonic and hyperbolic properties to encompass both linear polarizations.

  8. Identifying the perfect absorption of metamaterial absorbers

    Science.gov (United States)

    Duan, G.; Schalch, J.; Zhao, X.; Zhang, J.; Averitt, R. D.; Zhang, X.

    2018-01-01

    We present a detailed analysis of the conditions that result in unity absorption in metamaterial absorbers to guide the design and optimization of this important class of functional electromagnetic composites. Multilayer absorbers consisting of a metamaterial layer, dielectric spacer, and ground plane are specifically considered. Using interference theory, the dielectric spacer thickness and resonant frequency for unity absorption can be numerically determined from the functional dependence of the relative phase shift of the total reflection. Further, using transmission line theory in combination with interference theory we obtain analytical expressions for the unity absorption resonance frequency and corresponding spacer layer thickness in terms of the bare resonant frequency of the metamaterial layer and metallic and dielectric losses within the absorber structure. These simple expressions reveal a redshift of the unity absorption frequency with increasing loss that, in turn, necessitates an increase in the thickness of the dielectric spacer. The results of our analysis are experimentally confirmed by performing reflection-based terahertz time-domain spectroscopy on fabricated absorber structures covering a range of dielectric spacer thicknesses with careful control of the loss accomplished through water absorption in a semiporous polyimide dielectric spacer. Our findings can be widely applied to guide the design and optimization of the metamaterial absorbers and sensors.

  9. Novel Optical Metamaterials and Approaches for Fabrication

    Science.gov (United States)

    2012-08-01

    corresponding amino acids ................................................................................ 13 Figure 14: M13 Phage bound to silicon... phage display, we have also identified peptides that bind with nanoparticles and glass substrates. This is a critical step in engineering M13 ...the optical metamaterial. This technique employs the use of M13 bacteriophages [3], phages for short, which are viruses that infect bacteria and can

  10. Plasmonic waveguides cladded by hyperbolic metamaterials

    DEFF Research Database (Denmark)

    Ishii, Satoshi; Shalaginov, Mikhail Y.; Babicheva, Viktoriia E.

    2014-01-01

    Strongly anisotropic media with hyperbolic dispersion can be used for claddings of plasmonic waveguides (PWs). In order to analyze the fundamental properties of such waveguides, we analytically study 1D waveguides arranged from a hyperbolic metamaterial (HMM) in a HMM-Insulator-HMM (HIH) structur...

  11. MEMS for Tunable Photonic Metamaterial Applications

    Science.gov (United States)

    Stark, Thomas

    Photonic metamaterials are materials whose optical properties are derived from artificially-structured sub-wavelength unit cells, rather than from the bulk properties of the constituent materials. Examples of metamaterials include plasmonic materials, negative index materials, and electromagnetic cloaks. While advances in simulation tools and nanofabrication methods have allowed this field to grow over the past several decades, many challenges still exist. This thesis addresses two of these challenges: fabrication of photonic metamaterials with tunable responses and high-throughput nanofabrication methods for these materials. The design, fabrication, and optical characterization of a microelectromechanical systems (MEMS) tunable plasmonic spectrometer are presented. An array of holes in a gold film, with plasmon resonance in the mid-infrared, is suspended above a gold reflector, forming a Fabry-Perot interferometer of tunable length. The spectra exhibit the convolution of extraordinary optical transmission through the holes and Fabry-Perot resonances. Using MEMS, the interferometer length is modulated from 1.7 mum to 21.67 mum , thereby tuning the free spectral range from about 2900 wavenumbers to 230.7 wavenumbers and shifting the reflection minima and maxima across the infrared. Due to its broad spectral tunability in the fingerprint region of the mid-infrared, this device shows promise as a tunable biological sensing device. To address the issue of high-throughput, high-resolution fabrication of optical metamaterials, atomic calligraphy, a MEMS-based dynamic stencil lithography technique for resist-free fabrication of photonic metamaterials on unconventional substrates, has been developed. The MEMS consists of a moveable stencil, which can be actuated with nanometer precision using electrostatic comb drive actuators. A fabrication method and flip chip method have been developed, enabling evaporation of metals through the device handle for fabrication on an

  12. Metamaterials based on the phase transition of VO2.

    Science.gov (United States)

    Liu, Hongwei; Lu, Junpeng; Wang, Xiao Renshaw

    2018-01-12

    In this article, we present a comprehensive review on recent research progress in design and fabrication of active tunable metamaterials and devices based on phase transition of VO 2 . Firstly, we introduce mechanisms of the metal-to-insulator phase transition (MIPT) in VO 2 investigated by ultrafast THz spectroscopies. By analyzing the THz spectra, the evolutions of MIPT in VO 2 induced by different external excitations are described. The superiorities of using VO 2 as building blocks to construct highly tunable metamaterials are discussed. Subsequently, the recently demonstrated metamaterial devices based on VO 2 are reviewed. These metamaterials devices are summarized and described in the categories of working frequency. In each working frequency range, representative metamaterials based on VO 2 with different architectures and functionalities are reviewed and the contributions of the MIPT of VO 2 are emphasized. Finally, we conclude the recent reports and provide a prospect on the strategies of developing future tunable metamaterials based on VO 2 .

  13. Taming Light and Electrons with Metamaterials

    Science.gov (United States)

    Engheta, Nader

    2011-04-01

    In recent years, in my group we have been working on various aspects of metamaterials and plasmonic nano-optics. We have introduced and been developing the concept of "metatronics," i.e. metamaterial-inspired optical nanocircuitry, in which the three fields of "electronics," "photonics" and "magnetics" can be brought together seamlessly under one umbrella - a paradigm which I call the "Unified Paradigm of Metatronics." In this novel optical circuitry, the nanostructures with specific values of permittivity and permeability may act as the lumped circuit elements such as nanocapacitors, nanoinductors and nanoresistors. Nonlinearity in metatronics can also provide us with novel nonlinear lumped elements. We have investigated the concept of metatronics through extensive analytical and numerical studies, computer simulations, and recently in a set of experiments at the IR wavelengths. We have shown that nanorods made of low-stressed Si3N4 with properly designed cross sectional dimensions indeed function as lumped circuit elements at the IR wavelengths between 8 to 14 microns. We have been exploring how metamaterials can be exploited to control the flow of photons, analogous to what semiconductors do for electrons, providing the possibility of one-way flow of photons. We are now extending the concept of metatronics to other platforms such as graphene, which is a single atomically thin layer of carbon atoms, with unusual conductivity functions. We study the graphene as a new paradigm for metatronic circuitry and also as a "flatland" platform for IR metamaterials and transformation optics, leading to the concepts of one-atom-thick metamaterials, and one-atom-thick circuit elements and optical devices. I will give an overview of our most recent results in these fields.

  14. Reducing the losses of optical metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Anan [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    The field of metamaterials is driven by fascinating and far-reaching theoretical visions, such as perfect lenses, invisibility cloaking, and enhanced optical nonlinearities. However, losses have become the major obstacle towards real world applications in the optical regime. Reducing the losses of optical metamaterials becomes necessary and extremely important. In this thesis, two approaches are taken to reduce the losses. One is to construct an indefinite medium. Indefinite media are materials where not all the principal components of the permittivity and permeability tensors have the same sign. They do not need the resonances to achieve negative permittivity, ε. So, the losses can be comparatively small. To obtain indefinite media, three-dimensional (3D) optical metallic nanowire media with different structures are designed. They are numerically demonstrated that they are homogeneous effective indefinite anisotropic media by showing that their dispersion relations are hyperbolic. Negative group refraction and pseudo focusing are observed. Another approach is to incorporate gain into metamaterial nanostructures. The nonlinearity of gain is included by a generic four-level atomic model. A computational scheme is presented, which allows for a self-consistent treatment of a dispersive metallic photonic metamaterial coupled to a gain material incorporated into the nanostructure using the finite-difference time-domain (FDTD) method. The loss compensations with gain are done for various structures, from 2D simplified models to 3D realistic structures. Results show the losses of optical metamaterials can be effectively compensated by gain. The effective gain coefficient of the combined system can be much larger than the bulk gain counterpart, due to the strong local-field enhancement.

  15. Reducing the losses of optical metamaterials

    International Nuclear Information System (INIS)

    Fang, Anan

    2010-01-01

    The field of metamaterials is driven by fascinating and far-reaching theoretical visions, such as perfect lenses, invisibility cloaking, and enhanced optical nonlinearities. However, losses have become the major obstacle towards real world applications in the optical regime. Reducing the losses of optical metamaterials becomes necessary and extremely important. In this thesis, two approaches are taken to reduce the losses. One is to construct an indefinite medium. Indefinite media are materials where not all the principal components of the permittivity and permeability tensors have the same sign. They do not need the resonances to achieve negative permittivity, (var e psilon). So, the losses can be comparatively small. To obtain indefinite media, three-dimensional (3D) optical metallic nanowire media with different structures are designed. They are numerically demonstrated that they are homogeneous effective indefinite anisotropic media by showing that their dispersion relations are hyperbolic. Negative group refraction and pseudo focusing are observed. Another approach is to incorporate gain into metamaterial nanostructures. The nonlinearity of gain is included by a generic four-level atomic model. A computational scheme is presented, which allows for a self-consistent treatment of a dispersive metallic photonic metamaterial coupled to a gain material incorporated into the nanostructure using the finite-difference time-domain (FDTD) method. The loss compensations with gain are done for various structures, from 2D simplified models to 3D realistic structures. Results show the losses of optical metamaterials can be effectively compensated by gain. The effective gain coefficient of the combined system can be much larger than the bulk gain counterpart, due to the strong local-field enhancement.

  16. Recent Advances and Current Trends in Metamaterial-by-Design

    Science.gov (United States)

    Anselmi, N.; Gottardi, G.

    2018-02-01

    Thanks to their potential applications in several engineering areas, metamaterials gained much of attentions among different research communities, leading to the development of several analysis and synthesis tools. In this context, the metamaterial-by-design (MbD) paradigm has been recently introduced as a powerful tool for the design of complex metamaterials-based structures. In this work a review of the state-of-art, as well as the recent advancements of MbD-based methods are presented.

  17. Alignment-free three-dimensional optical metamaterials.

    Science.gov (United States)

    Zhao, Yang; Shi, Jinwei; Sun, Liuyang; Li, Xiaoqin; Alù, Andrea

    2014-03-05

    Three-dimensional optical metamaterials based on multilayers typically rely on critical vertical alignment to achieve the desired functionality. Here the conditions under which three-dimensional metamaterials with different functionalities may be realized without constraints on alignment are analyzed and demonstrated experimentally. This study demonstrates that the release of alignment constraints for multilayered metamaterials is allowed, while their anomalous interaction with light is preserved. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Hyperbolic polaritonic crystals based on nanostructured nanorod metamaterials.

    Science.gov (United States)

    Dickson, Wayne; Beckett, Stephen; McClatchey, Christina; Murphy, Antony; O'Connor, Daniel; Wurtz, Gregory A; Pollard, Robert; Zayats, Anatoly V

    2015-10-21

    Surface plasmon polaritons usually exist on a few suitable plasmonic materials; however, nanostructured plasmonic metamaterials allow a much broader range of optical properties to be designed. Here, bottom-up and top-down nanostructuring are combined, creating hyperbolic metamaterial-based photonic crystals termed hyperbolic polaritonic crystals, allowing free-space access to the high spatial frequency modes supported by these metamaterials. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Reconfiguring photonic metamaterials with currents and magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Valente, João, E-mail: jpv1f11@orc.soton.ac.uk; Ou, Jun-Yu; Plum, Eric, E-mail: erp@orc.soton.ac.uk [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Southampton SO17 1BJ (United Kingdom); Youngs, Ian J. [Physical Sciences Department, DSTL, Salisbury SP4 0JQ (United Kingdom); Zheludev, Nikolay I., E-mail: niz@orc.soton.ac.uk [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Southampton SO17 1BJ (United Kingdom); Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637378 (Singapore)

    2015-03-16

    We demonstrate that spatial arrangement and optical properties of metamaterial nanostructures can be controlled dynamically using currents and magnetic fields. Mechanical deformation of metamaterial arrays is driven by both resistive heating of bimorph nanostructures and the Lorentz force that acts on charges moving in a magnetic field. With electrically controlled transmission changes of up to 50% at sub-mW power levels, our approaches offer high contrast solutions for dynamic control of metamaterial functionalities in optoelectronic devices.

  20. A new metamaterial-based wideband rectangular invisibility cloak

    Science.gov (United States)

    Islam, S. S.; Hasan, M. M.; Faruque, M. R. I.

    2018-02-01

    A new metamaterial-based wideband electromagnetic rectangular cloak is being introduced in this study. The metamaterial unit cell shows sharp transmittances in the C- and X-bands and displays wideband negative effective permittivity region there. The metamaterial unit cell was then applied in designing a rectangular-shaped electromagnetic cloak. The scattering reduction technique was adopted for the cloaking operation. The cloak operates in the certain portion of C-and X-bands that covers more than 4 GHz bandwidth region. The experimental results were provided as well for the metamaterial and the cloak.

  1. Is it possible to homogenize resonant chiral metamaterials ?

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Menzel, Christoph; Rockstuhl, Carsten

    2010-01-01

    Homogenization of metamaterials is very important as it makes possible description in terms of effective parameters. In this contribution we consider the homogenization of chiral metamaterials. We show that for some metamaterials there is an optimal meta-atom size which depends on the coupling...... between meta-atoms. We introduce numerical criterion of homogeneity on the basis of the Bloch modes dispersion diagram calculation and a tool to predict the homogeneity limit. We show that some metamaterials with strong coupling between meta-atoms cannot be considered as homogeneous at all...

  2. Giant optical forces in planar dielectric photonic metamaterials.

    Science.gov (United States)

    Zhang, Jianfa; MacDonald, Kevin F; Zheludev, Nikolay I

    2014-08-15

    We demonstrate that resonant optical forces generated within all-dielectric planar photonic metamaterials at near-infrared illumination wavelengths can be an order of magnitude larger than in corresponding plasmonic metamaterials, reaching levels many tens of times greater than the force resulting from radiation pressure. This is made possible by the dielectric structures' freedom from Joule losses and the consequent ability to sustain Fano-resonances with high quality factors that are unachievable in plasmonic nanostructures. Dielectric nano-optomechanical metamaterials can thus provide a functional platform for a range of novel dynamically controlled and self-adaptive nonlinear, tunable/switchable photonic metamaterials.

  3. All-optical photonic band control in a quantum metamaterial

    Energy Technology Data Exchange (ETDEWEB)

    Felbacq, D.; Rousseau, E. [University of Montpellier, Laboratory Charles Coulomb UMR CNRS-UM 5221, Montpellier (France)

    2017-09-15

    Metamaterials made of periodic collections of dielectric nanorods are considered theoretically. When quantum resonators are embedded within the nanorods, one obtains a quantum metamaterial, whose electromagnetic properties depend upon the state of the quantum resonators. The theoretical model predicts that when the resonators are pumped and reach the inversion regime, the quantum metamaterial exhibits an all-optical switchable conduction band. The phenomenon can be described by considering the pole stucture of the scattering matrix of the metamaterial. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Disordered Plamonics and Complex Metamaterials

    KAUST Repository

    Gongora, J. S. Totero

    2017-05-01

    Complex systems are ensembles of interconnected elements where mutual interaction and an optimized amount of disorder produce advanced functionalities. These systems are abundant in our daily experience: typical examples are the brain, biological ecosystems, society, and finance. In the last century, researchers have investigated the fundamental properties of disordered systems, unveiling fascinating and counterintuitive dynamics. The main aim of this Dissertation is the study of a new platform of disorder-enhanced photonics systems, denoted as Complex Metamaterials. Due to its ultrafast time scale nanophotonics represents an ideal framework to investigate and harness complex dynamics. Starting from the theoretical modeling of disordered plasmonic systems, I discuss advanced real-life applications, including the generation of highly-resistant structural colors from porous metal surfaces and the realization of early-stage cancer detectors based on surface roughness and self-similarity. In addition to the effects of structural disorder on plasmonic systems I also investigate the complex emission dynamics from non-conventional nanolasers. Lasers represent the quintessential example of a complex photonic system due to the simultaneous presence of strong nonlinearities and multi-mode interactions. At the same time, the integration of nanolasers with silicon-based electronic circuitry represents one of the greatest technological challenges in the field of nanophotonics. By combining ab-initio simulations and analytical modeling, I characterize the nonlinear emission from three-dimensional plasmonic nanolasers known as SPASERs. My results show for the first time the occurrence of a spontaneous rotational emission in spherical SPASERs, which originates from the nonlinear interaction of several lasing modes. I further discuss how rotating nanolasers can be employed as a fundamental building block for integrated quantum simulators, random information sources, and brain

  5. Low-Loss and Broadband Metamaterials for Negative Index and Transformational Optics Applications

    Science.gov (United States)

    2012-05-22

    Quantum Dot Optical Metamaterials 3 3 Black Materials Based on Graphene Stacks 6... Dot Optical Metamaterials Realizing an active metamaterial composed of a semiconductor quantum dot ( QD ) and metal nanopar- ticle mixture provides... quantum dot metamaterials have yielded controllable 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 22-05-2012 13. SUPPLEMENTARY NOTES The

  6. Fano resonances from gradient-index metamaterials.

    Science.gov (United States)

    Xu, Yadong; Li, Sucheng; Hou, Bo; Chen, Huanyang

    2016-01-27

    Fano resonances - resonant scattering features with a characteristic asymmetric profile - have generated much interest, due to their extensive and valuable applications in chemical or biological sensors, new types of optical switches, lasers and nonlinear optics. They have been observed in a wide variety of resonant optical systems, including photonic crystals, metamaterials, metallic gratings and nanostructures. In this work, a waveguide structure is designed by employing gradient-index metamaterials, supporting strong Fano resonances with extremely sharp spectra. As the changes in the transmission spectrum originate from the interaction of guided modes from different channels, instead of resonance structures or metamolecules, the Fano resonances can be observed for both transverse electric and transverse magnetic polarizations. These findings are verified by fine agreement with analytical calculations and experimental results at microwave, as well as simulated results at near infrared frequencies.

  7. Topological mechanics of gyroscopic meta-materials

    Science.gov (United States)

    Irvine, William

    Topological mechanical meta-materials are artificial structures whose unusual properties are protected very much like their electronic and optical counterparts. I will present an experimental and theoretical study of a new kind of active meta-material comprised of coupled gyroscopes on a lattice that breaks time-reversal symmetry. The vibrational spectrum displays a sonic gap populated by topologically protected edge modes which propagate in only one direction and are unaffected by disorder. We observe these edge modes in experiment and verify their robustness to disorder and the insertion of obstacles. Controlled distortions of the underlying lattice can induce a topological phase transition that switches the edge mode chirality. This effect allows the direction of the edge current to be determined on demand.

  8. Active metamaterials terahertz modulators and detectors

    CERN Document Server

    Rout, Saroj

    2017-01-01

    This book covers the theoretical background and experimental methods for engineers and physicist to be able to design, fabricate and characterize terahertz devices using metamaterials. Devices utilize mainstream semiconductor foundry processes to make them for communication and imaging applications. This book will provide engineers and physicists a comprehensive reference to construct such devices with general background in circuits and electromagnetics. The authors describe the design and construction of electromagnetic (EM) devices for terahertz frequencies (108-1010cycles/sec) by embedding solid state electronic devices into artificial metamaterials where each unit cell is only a fraction of the wavelength of the incident EM wave. The net effect is an electronically tunable bulk properties with effective electric (permittivity) and magnetic (permeability) that can be utilized to make novel devices to fill the terahertz gap.

  9. An omnidirectional electromagnetic absorber made of metamaterials

    International Nuclear Information System (INIS)

    Cheng Qiang; Cui Tiejun; Jiang Weixiang; Cai Bengeng

    2010-01-01

    In a recent theoretical work by Narimanov and Kildishev (2009 Appl. Phys. Lett. 95 041106) an optical omnidirectional light absorber based on metamaterials was proposed, in which theoretical analysis and numerical simulations showed that all optical waves hitting the absorber are trapped and absorbed. Here we report the first experimental demonstration of an omnidirectional electromagnetic absorber in the microwave frequency. The proposed device is composed of non-resonant and resonant metamaterial structures, which can trap and absorb electromagnetic waves coming from all directions spirally inwards without any reflections due to the local control of electromagnetic fields. It is shown that the absorption rate can reach 99 per cent in the microwave frequency. The all-directional full absorption property makes the device behave like an 'electromagnetic black body', and the wave trapping and absorbing properties simulate, to some extent, an 'electromagnetic black hole.' We expect that such a device could be used as a thermal emitting source and to harvest electromagnetic waves.

  10. Graphene-enhanced metamaterials in THz applications

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Chigrin, Dmitry N.; Khromova, Irina

    electromagnetic waves makes them natural candidates for THz optical components [1]. However, ranges of light manipulation can be strongly expanded by involving graphene as a structural component of metamaterials. The interplay between interband and intraband transitions in graphene allows converting a multilayer...... graphene/dielectric structure into a transparent and/or electromagnetically dense artificial medium in a narrow THz or infra-red frequency range. The gate voltage can be used to electrically control the concentration of carriers in the graphene sheets and, thus, efficiently change the dispersion...... of the whole structure. Placed inside a hollow waveguide, a multilayer graphene/dielectric metamaterial provides high-speed modulation of radiation and offers novel concepts for terahertz modulators and tunable bandpass filters. We exemplify it showing performance of waveguide-based terahertz modulators...

  11. Bianisotropic metamaterials based on twisted asymmetric crosses

    International Nuclear Information System (INIS)

    Reyes-Avendaño, J A; Sampedro, M P; Juárez-Ruiz, E; Pérez-Rodríguez, F

    2014-01-01

    The effective bianisotropic response of 3D periodic metal-dielectric structures, composed of crosses with asymmetrically-cut wires, is investigated within a general homogenization theory using the Fourier formalism and the form-factor division approach. It is found that the frequency dependence of the effective permittivity for a system of periodically-repeated layers of metal crosses exhibits two strong resonances, whose separation is due to the cross asymmetry. Besides, bianisotropic metamaterials, having a base of four twisted asymmetric crosses, are proposed. The designed metamaterials possess negative refractive index at frequencies determined by the cross asymmetry, the gap between the arms of adjacent crosses lying on the same plane, and the type of Bravais lattice. (papers)

  12. Engineering photonic density of states using metamaterials

    DEFF Research Database (Denmark)

    Jacob, Z.; Kim, J.Y.; Naik, G.V.

    2010-01-01

    The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a......The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device...... such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial-based PDOS engineering....

  13. Wireless energy transfer between anisotropic metamaterials shells

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José, E-mail: jsdehesa@upv.es

    2014-06-15

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated. -- Highlights: •Anisotropic metamaterial shells exhibit high quality factors and sub-wavelength size. •Exchange of electromagnetic energy between shells with high efficiency is analyzed. •Strong coupling is supported with high wireless transfer efficiency. •End-to-end energy transfer efficiencies higher than 83% can be predicted.

  14. Circuit Model of Gain in Metamaterials

    Science.gov (United States)

    Boardman, Allan D.; King, Neil; Rapoport, Yuriy

    Metamaterials embody exciting prospects for a new generation of novel photonic devices. From their initial emergence as a physical construct in the GHz domain at the start of the 21st century [1-3], they have attracted a significant amount of global interest [4-13] with considerable effort being undertaken to extend their operation into the THz window and even optical regimes [14,15]. However, as they stand, early theoretical indications are that losses will cause potential problems for all possible frequencies and, in particular, kill any opportunity [16] for a useful metamaterial operating around and above 30THz. Such losses are inevitably closely linked to the resonant behaviour of the metaparticles and is addressed here by the placement of active diodes onto a form of metallic split-ring. The use of diodes to create a nonlinear magnetic response [16] and to create tunability [17] has already been discussed but active diodes [18] not only promise means of reducing losses but they can be deployed to produce an overall gain [19]. This behaviour is readily scalable from GHz to THz and even to nanowire [20] and nanoparticle-based metamaterials [21] operating in the optical frequency window. Nevertheless, it is highlighted here that instabilities could present a serious issue. From an investigation of the dispersion relation for a plane wave, a number of conditions are derived that identify the limits placed upon the system parameters, in order to ensure stable overall gain. Any examination of loss, or gain, must, however, be conducted from the perspective of the entire metamaterial, including the permittivity. Depending on the level of sophistication required in the fabrication technique, split-rings may be engineered with different shapes and deployed in a number of different arrays. The most popular have either a circular, or square shape. The term "split-ring" is treated here as a generic name and is not necessarily indicative of a specific shape.

  15. Nano metamaterials for ultrasensitive Terahertz biosensing

    OpenAIRE

    Lee, Dong-Kyu; Kang, Ji-Hun; Kwon, Junghoon; Lee, Jun-Seok; Lee, Seok; Woo, Deok Ha; Kim, Jae Hun; Song, Chang-Seon; Park, Q-Han; Seo, Minah

    2017-01-01

    As a candidate for a rapid detection of biomaterials, terahertz (THz) spectroscopy system can be considered with some advantage in non-destructive, label-free, and non-contact manner. Because protein-ligand binding energy is in the THz range, especially, most important conformational information in molecular interactions can be captured by THz electromagnetic wave. Based on the THz time-domain spectroscopy system, THz nano-metamaterial sensing chips were prepared for great enhancing of detect...

  16. Broadband dielectric terahertz metamaterials with negative permeability

    Czech Academy of Sciences Publication Activity Database

    Yahiaoui, R.; Němec, Hynek; Kužel, Petr; Kadlec, Filip; Kadlec, Christelle; Mounaix, P.

    2009-01-01

    Roč. 34, č. 22 (2009), s. 3541-3543 ISSN 0146-9592 R&D Projects: GA AV ČR(CZ) IAA100100907; GA MŠk LC512 Institutional research plan: CEZ:AV0Z10100520 Keywords : effective response * terahertz metamaterial * dielectric array Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.059, year: 2009 http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-34-22-3541

  17. Tunable terahertz metamaterials with negative permeability

    Czech Academy of Sciences Publication Activity Database

    Němec, Hynek; Kužel, Petr; Kadlec, Filip; Kadlec, Christelle; Yahiaoui, R.; Mounaix, P.

    2009-01-01

    Roč. 79, č. 24 (2009), 241108/1-241108/4 ISSN 1098-0121 R&D Projects: GA AV ČR(CZ) IAA100100907; GA MŠk LC512; GA MŠk MEB020742 Institutional research plan: CEZ:AV0Z10100520 Keywords : tunable metamaterial * effective magnetic permeability * incipient ferroelectrics * strontium titanate * terahertz spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

  18. Photoconductive metamaterials with giant plasmonic photogalvanic effect

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Babicheva, Viktoriia; Evlyuknin, Andrey B.

    2014-01-01

    Photoelectric properties of metamaterials comprising oriented noncentrosymmetric metallic nanoparticle arrays in a homogeneous semiconductor matrix are theoretically studied. When uniformly illuminated by a plane wave, the asymmetric shape of the nanoparticles results in electro-motive force...... and photocurrent without any external potential. This is the direct analogue of the photogalvanic effect existing in ferroelectric or piezoelectric crystals, e.g., bismuth ferrite. The reported plasmonic photogalvanic effect is valuable for characterizing photoconductive properties of plasmonic nanostructures...

  19. Plasmonic waveguides cladded by hyperbolic metamaterials.

    Science.gov (United States)

    Ishii, Satoshi; Shalaginov, Mikhail Y; Babicheva, Viktoriia E; Boltasseva, Alexandra; Kildishev, Alexander V

    2014-08-15

    Strongly anisotropic media with hyperbolic dispersion can be used for claddings of plasmonic waveguides (PWs). In order to analyze the fundamental properties of such waveguides, we analytically study 1D waveguides arranged from a hyperbolic metamaterial (HMM) in a HMM-Insulator-HMM (HIH) structure. We show that HMM claddings give flexibility in designing the properties of HIH waveguides. Our comparative study on 1D PWs reveals that HIH-type waveguides can have a higher performance than MIM or IMI waveguides.

  20. Perforated membrane-type acoustic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Langfeldt, F., E-mail: Felix.Langfeldt@haw-hamburg.de [Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, Berliner Tor 9, D-20099 Hamburg (Germany); Kemsies, H., E-mail: Hannes.Kemsies@haw-hamburg.de [Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, Berliner Tor 9, D-20099 Hamburg (Germany); Gleine, W., E-mail: Wolfgang.Gleine@haw-hamburg.de [Department of Automotive and Aeronautical Engineering, Hamburg University of Applied Sciences, Berliner Tor 9, D-20099 Hamburg (Germany); Estorff, O. von, E-mail: estorff@tu-harburg.de [Institute of Modelling and Computation, Hamburg University of Technology, Denickestr. 17, D-21073 Hamburg (Germany)

    2017-04-25

    This letter introduces a modified design of membrane-type acoustic metamaterials (MAMs) with a ring mass and a perforation so that an airflow through the membrane is enabled. Simplified analytical investigations of the perforated MAM (PMAM) indicate that the perforation introduces a second anti-resonance, where the effective surface mass density of the PMAM is much higher than the static value. The theoretical results are validated using impedance tube measurements, indicating good agreement between the theoretical predictions and the measured data. The anti-resonances yield high low-frequency sound transmission loss values with peak values over 25 dB higher than the corresponding mass-law. - Highlights: • A new membrane-type acoustic metamaterial exhibiting negative density is presented. • The metamaterial design contains a ring mass with a perforation through the membrane. • The sound transmission loss exhibits narrow-band peaks much higher than the mass-law. • The emergence of the peaks is explained using a simple theoretical model. • Impedance tube measurements are used to validate the theoretical predictions.

  1. Graphene plasmonics for tunable terahertz metamaterials.

    Science.gov (United States)

    Ju, Long; Geng, Baisong; Horng, Jason; Girit, Caglar; Martin, Michael; Hao, Zhao; Bechtel, Hans A; Liang, Xiaogan; Zettl, Alex; Shen, Y Ron; Wang, Feng

    2011-09-04

    Plasmons describe collective oscillations of electrons. They have a fundamental role in the dynamic responses of electron systems and form the basis of research into optical metamaterials. Plasmons of two-dimensional massless electrons, as present in graphene, show unusual behaviour that enables new tunable plasmonic metamaterials and, potentially, optoelectronic applications in the terahertz frequency range. Here we explore plasmon excitations in engineered graphene micro-ribbon arrays. We demonstrate that graphene plasmon resonances can be tuned over a broad terahertz frequency range by changing micro-ribbon width and in situ electrostatic doping. The ribbon width and carrier doping dependences of graphene plasmon frequency demonstrate power-law behaviour characteristic of two-dimensional massless Dirac electrons. The plasmon resonances have remarkably large oscillator strengths, resulting in prominent room-temperature optical absorption peaks. In comparison, plasmon absorption in a conventional two-dimensional electron gas was observed only at 4.2 K (refs 13, 14). The results represent a first look at light-plasmon coupling in graphene and point to potential graphene-based terahertz metamaterials.

  2. Experiments on seismic metamaterials: molding surface waves.

    Science.gov (United States)

    Brûlé, S; Javelaud, E H; Enoch, S; Guenneau, S

    2014-04-04

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations.

  3. Elastic metamaterial beam with remotely tunable stiffness

    Science.gov (United States)

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-02-01

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ˜30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves.

  4. Nano metamaterials for ultrasensitive Terahertz biosensing.

    Science.gov (United States)

    Lee, Dong-Kyu; Kang, Ji-Hun; Kwon, Junghoon; Lee, Jun-Seok; Lee, Seok; Woo, Deok Ha; Kim, Jae Hun; Song, Chang-Seon; Park, Q-Han; Seo, Minah

    2017-08-15

    As a candidate for a rapid detection of biomaterials, terahertz (THz) spectroscopy system can be considered with some advantage in non-destructive, label-free, and non-contact manner. Because protein-ligand binding energy is in the THz range, especially, most important conformational information in molecular interactions can be captured by THz electromagnetic wave. Based on the THz time-domain spectroscopy system, THz nano-metamaterial sensing chips were prepared for great enhancing of detection sensitivity. A metamaterial sensing chip was designed for increasing of absorption cross section of the target sample, related to the transmitted THz near field enhancement via the composition of metamaterial. The measured THz optical properties were then analyzed in terms of refractive index and absorption coefficient, and compared with simulation results. Also, virus quantification regarding various concentrations of the viruses was performed, showing a clear linearity. The proposed sensitive and selective THz detection method can provide abundant information of detected biomaterials to help deep understanding of fundamental optical characteristics of them, suggesting rapid diagnosis way especially useful for such dangerous and time-sensitive target biomaterials.

  5. Review of Plasmonic Nanocomposite Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Mehdi Keshavarz Hedayati

    2014-02-01

    Full Text Available Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon. These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented.

  6. Review of Plasmonic Nanocomposite Metamaterial Absorber

    Science.gov (United States)

    Hedayati, Mehdi Keshavarz; Faupel, Franz; Elbahri, Mady

    2014-01-01

    Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface _lasmon). These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on) perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented. PMID:28788511

  7. Elastic metamaterial beam with remotely tunable stiffness

    International Nuclear Information System (INIS)

    Qian, Wei; Yu, Zhengyue; Wang, Xiaole; Lai, Yun; Yellen, Benjamin B.

    2016-01-01

    We demonstrate a dynamically tunable elastic metamaterial, which employs remote magnetic force to adjust its vibration absorption properties. The 1D metamaterial is constructed from a flat aluminum beam milled with a linear array of cylindrical holes. The beam is backed by a thin elastic membrane, on which thin disk-shaped permanent magnets are mounted. When excited by a shaker, the beam motion is tracked by a Laser Doppler Vibrometer, which conducts point by point scanning of the vibrating element. Elastic waves are unable to propagate through the beam when the driving frequency excites the first elastic bending mode in the unit cell. At these frequencies, the effective mass density of the unit cell becomes negative, which induces an exponentially decaying evanescent wave. Due to the non-linear elastic properties of the membrane, the effective stiffness of the unit cell can be tuned with an external magnetic force from nearby solenoids. Measurements of the linear and cubic static stiffness terms of the membrane are in excellent agreement with experimental measurements of the bandgap shift as a function of the applied force. In this implementation, bandgap shifts by as much as 40% can be achieved with ∼30 mN of applied magnetic force. This structure has potential for extension in 2D and 3D, providing a general approach for building dynamically tunable elastic metamaterials for applications in lensing and guiding elastic waves

  8. Experiments on Seismic Metamaterials: Molding Surface Waves

    Science.gov (United States)

    Brûlé, S.; Javelaud, E. H.; Enoch, S.; Guenneau, S.

    2014-04-01

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations.

  9. A Broadband Ultrathin Nonlinear Switching Metamaterial

    Directory of Open Access Journals (Sweden)

    E. Zarnousheh Farahani

    2017-05-01

    Full Text Available In this paper, an ultrathin planar nonlinear metamaterial slab is designed and simulated. Nonlinearity is provided through placing diodes in each metamaterial unit cell. The diodes are auto-biased and activated by an incident wave. The proposed structure represents a broadband switching property between two transmission and reflection states depending on the intensity of the incident wave. High permittivity values are presented creating a near zero effective impedance at low power states, around the second resonant mode of the structure unit cell; as the result, the incident wave is reflected. Increasing the incident power to the level which can activate the loaded diodes in the structure results in elimination of the resonance and consequently a drop in the permittivity values near the permeability one as well as a switch to the transmission state. A full wave as well as a nonlinear simulations are performed. An optimization method based on weed colonization is applied to the unit cell of the metamaterial slab to achieve the maximum switching bandwidth. The structure represents a 24% switching bandwidth of a 10 dB reduction in the reflection coefficient.

  10. Magnetic response of split-ring resonator metamaterials: From ...

    Indian Academy of Sciences (India)

    The SRR allows the generation of a magnetic resonance and a negative permeability band which depends on the geometry of the structure. The functioning of SRR-based metamaterials has been explained using an LC-circuit paradigm [4]. SRR, or its vari- ants such as fish-net metamaterials [7], are the primary producers ...

  11. Absorption and dispersion in metamaterials: Feasibility of device ...

    Indian Academy of Sciences (India)

    We present a quantitative study of the effects of losses in layered media with a metamaterial layer as the constituent. The metamaterial is modelled by a causal isotropic effective medium (Lorentz-type) response. The parameters for the model are picked from a recent experiment. Two specific examples, namely, that of ...

  12. Conservation laws for perturbed solitons in optical metamaterials

    Directory of Open Access Journals (Sweden)

    Anjan Biswas

    2018-03-01

    Full Text Available The conservation laws for the dynamics of soliton propagation through optical metamaterials are derived by the aid of Lie symmetry analysis. The proposed model will be studied with two forms of nonlinearity. They are Kerr law and parabolic law. Keywords: Conservation laws, Lie symmetry, Optical metamaterials

  13. Metamaterials in microwaves, optics, mechanics, thermodynamics, and transport

    Science.gov (United States)

    Koschny, Thomas; Soukoulis, Costas M.; Wegener, Martin

    2017-08-01

    We review the status of metamaterials on the occasion of the 15th birthday of the field with particular emphasis on our own contributions. Metamaterials in electromagnetism, mechanics, thermodynamics, and transport are covered. We emphasize that 3D printing, also known as additive manufacturing, inspires metamaterials—and vice versa.

  14. Hybrid antiresonant metamaterial waveguides for THz and IR

    DEFF Research Database (Denmark)

    Stefani, Alessio; Lwin, Richard; Argyros, Alexander

    2016-01-01

    We report on a novel waveguide concept which combines antiresonant and metamaterial guidance. The guidance is achieved in the hollow core and loss as low as 2.3 dB/km are theoretically achievable in the THz frequency range. Both purely antiresonant and antiresonant metamaterial fibers have been f...

  15. Fiber-Drawn Metamaterial for THz Waveguiding and Imaging

    DEFF Research Database (Denmark)

    Atakaramians, Shaghik; Stefani, Alessio; Li, Haisu

    2017-01-01

    In this paper, we review the work of our group in fabricating metamaterials for terahertz (THz) applications by fiber drawing. We discuss the fabrication technique and the structures that can be obtained before focusing on two particular applications of terahertz metamaterials, i.e., waveguiding...

  16. Arbitrarily thin metamaterial structure for perfect absorption and giant magnification

    DEFF Research Database (Denmark)

    Jin, Yi; Xiao, Sanshui; Mortensen, N. Asger

    2011-01-01

    layer can perfectly absorb or giantly amplify an incident plane wave at a critical angle when the real parts of the permittivity and permeability of the metamaterial are zero while the absolute imaginary parts can be arbitrarily small. The metamaterial layer needs a totally reflective substrate...

  17. Broadband room temperature strong coupling between quantum dots and metamaterials.

    Science.gov (United States)

    Indukuri, Chaitanya; Yadav, Ravindra Kumar; Basu, J K

    2017-08-17

    Herein, we report the first demonstration of room temperature enhanced light-matter coupling in the visible regime for metamaterials using cooperative coupled quasi two dimensional quantum dot assemblies located at precise distances from the hyperbolic metamaterial (HMM) templates. The non-monotonic variation of the magnitude of strong coupling, manifested in terms of strong splitting of the photoluminescence of quantum dots, can be explained in terms of enhanced LDOS near the surface of such metamaterials as well as the plasmon mediated super-radiance of closely spaced quantum dots (QDs). Our methodology of enhancing broadband, room temperature, light-matter coupling in the visible regime for metamaterials opens up new possibilities of utilising these materials for a wide range of applications including QD based thresholdless nanolasers and novel metamaterial based integrated photonic devices.

  18. Characterization of Meta-Materials Using Computational Electromagnetic Methods

    Science.gov (United States)

    Deshpande, Manohar; Shin, Joon

    2005-01-01

    An efficient and powerful computational method is presented to synthesize a meta-material to specified electromagnetic properties. Using the periodicity of meta-materials, the Finite Element Methodology (FEM) is developed to estimate the reflection and transmission through the meta-material structure for a normal plane wave incidence. For efficient computations of the reflection and transmission over a wide band frequency range through a meta-material a Finite Difference Time Domain (FDTD) approach is also developed. Using the Nicholson-Ross method and the Genetic Algorithms, a robust procedure to extract electromagnetic properties of meta-material from the knowledge of its reflection and transmission coefficients is described. Few numerical examples are also presented to validate the present approach.

  19. Plasmonic metamaterial absorber for broadband manipulation of mechanical resonances

    Science.gov (United States)

    Zhu, Hai; Yi, Fei; Cubukcu, Ertugrul

    2016-11-01

    Metamaterials are artificial materials that exhibit unusual properties for electromagnetic and sound waves. The quanta, namely photons and phonons, of these waves interact resonantly with these exotic man-made materials enabling many applications. For instance, resonant light absorption in photonic metamaterials can efficiently convert optical energy into heat based on the photothermal effect. Here, we present a plasmonic metamaterial that simultaneously supports thermomechanically coupled optical and mechanical resonances for controlling mechanical damping with light. In this metamaterial absorber with voltage-tunable Fano resonances, we experimentally achieve optically pumped coherent mechanical oscillations based on a plasmomechanical parametric gain mechanism over an ∼4 THz bandwidth. Through the reverse effect, optical damping of mechanical resonance is also achieved. Our results provide a metamaterial-based approach for optical manipulation of the dynamics of mechanical oscillators.

  20. Effective Medium Theory for Anisotropic Metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2017-11-12

    This dissertation includes the study of effective medium theories (EMTs) and their applications in describing wave propagation in anisotropic metamaterials, which can guide the design of metamaterials. An EMT based on field averaging is proposed to describe a peculiar anisotropic dispersion relation that is linear along the symmetry line but quadratic in the perpendicular direction. This dispersion relation is associated with the topological transition of the iso-frequency contours (IFCs), suggesting interesting wave propagation behaviors from beam shaping to beam splitting. In the framework of coherent potential approximation, an analytical EMT is further developed, with the ability to build a direct connection between the microscopic structure and the macroscopic material properties, which overcomes the requirement of prior knowledge of the field distributions. The derived EMT is valid beyond the long-wavelength limit. Using the EMT, an anisotropic zero-index metamaterial is designed. Moreover, the derived EMT imposes a condition that no scattered wave is generated in the ambient medium, which suggests the input signal cannot detect any object that might exist, making it invisible. Such correspondence between the EMT and the invisibilityinspires us to explore the wave cloaking in the same framework of coherent potential approximation. To further broaden the application realm of EMT, an EMT using the parameter retrieval method is studied in the regimes where the previously-developed EMTs are no longer accurate. Based on this study, in conjunction with the EMT mentioned above, a general scheme to realize coherent perfect absorption (CPA) in anisotropic metamaterials is proposed. As an exciting area in metamaterials, the field of metasurfaces has drawn great attention recently. As an easily attainable device, a grating may be the simplest version of metasurfaces. Here, an analytical EMT for gratings made of cylinders is developed by using the multiple scattering

  1. A Summary of Recent Developments on Metamaterial-based and Metamaterial-inspired Efficient Electrically Small Antennas

    DEFF Research Database (Denmark)

    Erentok, Aycan; Ziolkowski, Richard W.

    2008-01-01

    of the radiation and resonance behaviors of the proposed metamaterial-based EESA systems, as well as our efforts to conceptualize structures which might be used to build them, have led to the discovery of several realizable metamaterial-inspired EESA systems. The measurement results confirm the numerical...

  2. Dual-channel spontaneous emission of quantum dots in magnetic metamaterials.

    Science.gov (United States)

    Decker, Manuel; Staude, Isabelle; Shishkin, Ivan I; Samusev, Kirill B; Parkinson, Patrick; Sreenivasan, Varun K A; Minovich, Alexander; Miroshnichenko, Andrey E; Zvyagin, Andrei; Jagadish, Chennupati; Neshev, Dragomir N; Kivshar, Yuri S

    2013-01-01

    Metamaterials, artificial electromagnetic media realized by subwavelength nano-structuring, have become a paradigm for engineering electromagnetic space, allowing for independent control of both electric and magnetic responses of the material. Whereas most metamaterials studied so far are limited to passive structures, the need for active metamaterials is rapidly growing. However, the fundamental question on how the energy of emitters is distributed between both (electric and magnetic) interaction channels of the metamaterial still remains open. Here we study simultaneous spontaneous emission of quantum dots into both of these channels and define the control parameters for tailoring the quantum-dot coupling to metamaterials. By superimposing two orthogonal modes of equal strength at the wavelength of quantum-dot photoluminescence, we demonstrate a sharp difference in their interaction with the magnetic and electric metamaterial modes. Our observations reveal the importance of mode engineering for spontaneous emission control in metamaterials, paving a way towards loss-compensated metamaterials and metamaterial nanolasers.

  3. Automated design of infrared digital metamaterials by genetic algorithm

    Science.gov (United States)

    Sugino, Yuya; Ishikawa, Atsushi; Hayashi, Yasuhiko; Tsuruta, Kenji

    2017-08-01

    We demonstrate automatic design of infrared (IR) metamaterials using a genetic algorithm (GA) and experimentally characterize their IR properties. To implement the automated design scheme of the metamaterial structures, we adopt a digital metamaterial consisting of 7 × 7 Au nano-pixels with an area of 200 nm × 200 nm, and their placements are coded as binary genes in the GA optimization process. The GA combined with three-dimensional (3D) finite element method (FEM) simulation is developed and applied to automatically construct a digital metamaterial to exhibit pronounced plasmonic resonances at the target IR frequencies. Based on the numerical results, the metamaterials are fabricated on a Si substrate over an area of 1 mm × 1 mm by using an EB lithography, Cr/Au (2/20 nm) depositions, and liftoff process. In the FT-IR measurement, pronounced plasmonic responses of each metamaterial are clearly observed near the targeted frequencies, although the synthesized pixel arrangements of the metamaterials are seemingly random. The corresponding numerical simulations reveal the important resonant behavior of each pixel and their hybridized systems. Our approach is fully computer-aided without artificial manipulation, thus paving the way toward the novel device design for next-generation plasmonic device applications.

  4. Optical metamaterials with quasicrystalline symmetry: symmetry-induced optical isotropy

    International Nuclear Information System (INIS)

    Kruk, S.S.; Decker, M.; Helgert, Ch.; Neshev, D.N.; Kivshar, Y.S.; Staude, I.; Powell, D.A.; Pertsch, Th.; Menzel, Ch.; Helgert, Ch.; Etrich, Ch.; Rockstuhl, C.; Menzel, Ch.

    2013-01-01

    Taking advantage of symmetry considerations, we have analyzed the potential of various metamaterials to affect the polarization state of light upon oblique illumination. We have shown that depending on the angle of illumination, metamaterials are able to support specific polarization states. The presented methodology that using ellipticity and circular dichroism, provides an unambiguous language for discussing the impact of the inherent symmetry of the metamaterial lattices on their far-field response. Our findings allow the quantification analysis of the impact of inter-element coupling and lattice symmetry on the optical properties of metamaterials, and to separate this contribution from the response associated with a single meta-atom. In addition, we have studied the concept of optical quasicrystalline metamaterials, revealing that the absence of translational symmetry (periodicity) of quasicrystalline metamaterials causes an isotropic optical response, while the long-range positional order preserves the resonance properties. Our findings constitute an important step towards the design of optically isotropic metamaterials and metasurfaces. (authors)

  5. Customized shaping of vibration modes by acoustic metamaterial synthesis

    Science.gov (United States)

    Xu, Jiawen; Li, Shilong; Tang, J.

    2018-04-01

    Acoustic metamaterials have attractive potential in elastic wave guiding and attenuation over specific frequency ranges. The vast majority of related investigations are on transient waves. In this research we focus on stationary wave manipulation, i.e., shaping of vibration modes. Periodically arranged piezoelectric transducers shunted with inductive circuits are integrated to a beam structure to form a finite-length metamaterial beam. We demonstrate for the first time that, under a given operating frequency of interest, we can facilitate a metamaterial design such that this frequency becomes a natural frequency of the integrated system. Moreover, the vibration mode corresponding to this natural frequency can be customized and shaped to realize tailored/localized response distribution. This is fundamentally different from previous practices of utilizing geometry modification and/or feedback control to achieve mode tailoring. The metamaterial design is built upon the combinatorial effects of the bandgap feature and the effective resonant cavity feature, both attributed to the dynamic characteristics of the metamaterial beam. Analytical investigations based on unit-cell dynamics and modal analysis of the metamaterial beam are presented to reveal the underlying mechanism. Case illustrations are validated by finite element analyses. Owing to the online tunability of circuitry integrated, the proposed mode shaping technique can be online adjusted to fit specific requirements. The customized shaping of vibration modes by acoustic metamaterial synthesis has potential applications in vibration suppression, sensing enhancement and energy harvesting.

  6. Seismic metamaterials based on isochronous mechanical oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Finocchio, G., E-mail: gfinocchio@unime.it; Garescì, F.; Azzerboni, B. [Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, C.da di Dio, I-98166 Messina (Italy); Casablanca, O.; Chiappini, M. [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via Vigna Murata 605, 00143 Roma (Italy); Ricciardi, G. [Department of Civil, Informatic, Architectural, and Environmental Engineering and Applied Mathematics, C.da di Dio, I-98166 Messina (Italy); Alibrandi, U. [Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576 (Singapore)

    2014-05-12

    This Letter introduces a seismic metamaterial (SM) composed by a chain of mass-in-mass system able to filter the S-waves of an earthquake. We included the effect of the SM into the mono dimensional model for the soil response analysis. The SM modifies the soil behavior and in presence of an internal damping the amplitude of the soil amplification function is reduced also in a region near the resonance frequency. This SM can be realized by a continuous structure with inside a 3d-matrix of isochronous oscillators based on a sphere rolling over a cycloidal trajectory.

  7. Ergoregion in metamaterials mimicking a Kerr spacetime

    Science.gov (United States)

    Pires, D. G.; Rocha, J. C. A.; Brandão, P. A.

    2018-02-01

    We propose a simple singularity-free coordinate transformation that could be implemented in Maxwell’s equations in order to simulate one aspect of a Kerr black hole. Kerr black holes are known to force light to rotate in a predetermined direction inside the ergoregion. By making use of cosmological analogies and the theoretical framework of transformation optics, we have designed a metamaterial that can make light behave as if it is propagating around a rotating cosmological massive body. We present numerical simulations involving incident Gaussian beams interacting with the materials to verify our predictions. The ergoregion is defined through the dispersion curve of the off-axis permittivities components.

  8. Guided modes of elliptical metamaterial waveguides

    International Nuclear Information System (INIS)

    Halterman, Klaus; Feng, Simin; Overfelt, P. L.

    2007-01-01

    The propagation of guided electromagnetic waves in open elliptical metamaterial waveguide structures is investigated. The waveguide contains a negative-index media core, where the permittivity ε and permeability μ are negative over a given bandwidth. The allowed mode spectrum for these structures is numerically calculated by solving a dispersion relation that is expressed in terms of Mathieu functions. By probing certain regions of parameter space, we find the possibility exists to have extremely localized waves that transmit along the surface of the waveguide

  9. Impedance matched thin metamaterials make metals absorbing.

    Science.gov (United States)

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-11-13

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin ( 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

  10. Polymeric matrix materials for infrared metamaterials

    Science.gov (United States)

    Dirk, Shawn M; Rasberry, Roger D; Rahimian, Kamyar

    2014-04-22

    A polymeric matrix material exhibits low loss at optical frequencies and facilitates the fabrication of all-dielectric metamaterials. The low-loss polymeric matrix material can be synthesized by providing an unsaturated polymer, comprising double or triple bonds; partially hydrogenating the unsaturated polymer; depositing a film of the partially hydrogenated polymer and a crosslinker on a substrate; and photopatterning the film by exposing the film to ultraviolet light through a patterning mask, thereby cross-linking at least some of the remaining unsaturated groups of the partially hydrogenated polymer in the exposed portions.

  11. Cylindrical metamaterial-based subwavelength antenna

    DEFF Research Database (Denmark)

    Erentok, Aycan; Kim, Oleksiy S.; Arslanagic, Samel

    2009-01-01

    A subwavelength monopole antenna radiating in the presence of a truncated cylindrical shell, which has a capped top face and is made of a negative permittivity metamaterial, is analyzed numerically by a method of moments for the volume-surface integral equation oil the one hand, and a finite...... element method on the other hand. It is shown that a center-fed truncated cylinder, in contrast to an infinite cylinder, provides subwavelength resonances, thus suggesting the possibility, of having a subwavelength antenna system....

  12. Bulk metamaterials: Design, fabrication and characterization

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Alabastri, Alessandro

    2009-01-01

    Bulk metamaterials claim a lot of attention worldwide. We report about our activity and advances in design, fabrication and characterization of metal-dielectric composites with three-dimensional lattices. The nomenclature of designs exhibiting negative index behaviour in the near infrared includes...... ambiguity generic to the standard S-parameters retrieval method. Accurateness of the method is highlighted by a set of numerical checks. To fabricate smooth metal three-dimensional structures we develop an electroless chemical technique. We present the results of silver deposition on the surface of a 30...

  13. A 3D Optical Metamaterial Made by Self-Assembly

    KAUST Repository

    Vignolini, Silvia

    2011-10-24

    Optical metamaterials have unusual optical characteristics that arise from their periodic nanostructure. Their manufacture requires the assembly of 3D architectures with structure control on the 10-nm length scale. Such a 3D optical metamaterial, based on the replication of a self-assembled block copolymer into gold, is demonstrated. The resulting gold replica has a feature size that is two orders of magnitude smaller than the wavelength of visible light. Its optical signature reveals an archetypal Pendry wire metamaterial with linear and circular dichroism. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Metamaterial inspired electromagnetic applications role of intelligent systems

    CERN Document Server

    2017-01-01

    This book focuses on the role of soft-computing-based electromagnetic computational engines in design and optimization of a wide range of electromagnetic applications. In addition to the theoretical background of metamaterials and soft-computing techniques, the book discusses novel electromagnetic applications such as tensor analysis for invisibility cloaking, metamaterial structures for cloaking applications, broadband radar absorbers, and antennas. The book will prove to be a valuable resource for academics and professionals, as well as military researchers working in the area of metamaterials.

  15. Asymmetric transmission of a planar metamaterial induced by symmetry breaking

    Science.gov (United States)

    Bai, Yu; Chen, Yuyan; Zhang, Yongyuan; Wang, Yongkai; Aba, Tudahong; Li, Hui; Wang, Li; Zhang, Zhongyue

    2018-03-01

    Asymmetric transmission (AT) is widely used in polarization transformers and polarization-controlled devices. In this paper, a planar metamaterial nanostructure with connected gammadion-shaped nanostructure (CGN) is proposed to achieve AT effect for forward and backward propagations of circular polarized light. The CGN arrays can produce magnetic moment oscillation that is normal to the metamaterial plane, which is weakly coupled to free space and generates transmission valleys. The introduction of symmetry breaking exerts a strong influence on the AT effects, and these effects can be tuned by the structural parameters. Our planar metamaterials may have potential for application in the future design of polarization-controlling devices.

  16. Acoustic Luneburg lens using orifice-type metamaterial unit cells

    Science.gov (United States)

    Park, Choon Mahn; Lee, Sang Hun

    2018-02-01

    A two-dimensional acoustic Luneburg lens that can be easily expanded into a three-dimensional sphere is fabricated. The required spatial distribution of the refractive index for this Luneburg lens is realized using the characteristics of orifice-type metamaterial unit cells. Typical characteristics of the resulting acoustic Luneburg lens, such as its aberration-free performance and capability for antipodal focusing of the lens for the incident plane waves, are investigated through experiments and simulations with the attenuation loss at frequencies that satisfy the homogeneous medium condition of the metamaterial. With the designed metamaterial, we achieved the minimum spot that lies within the classical diffraction limit at the focal point.

  17. Development and Application of Acoustic Metamaterials with Locally Resonant Microstructures

    Science.gov (United States)

    2014-10-21

    metamaterials can be fully understood. Moreover, more microstructures for metamaterials will be designed and stidied. The 3D printing technology will be...in the time and frequency domain than any other wavelets based on Heisenberg Uncertainty. 41 (a) (b) Fig. 6.7 The magnitudes of WT...in Tables 7.1 – 7.3, respectively. The three types of metamaterials were fabricated with a 3D printer using a polymer ink. Figs 7.4 and 7.5 show a

  18. Graphene metamaterials based tunable terahertz absorber: effective surface conductivity approach

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Lavrinenko, Andrei

    2013-01-01

    In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity...... we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers.......In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity...

  19. Vortexlike Power Flow at the Interfaces of Metamaterial Lens

    Directory of Open Access Journals (Sweden)

    K. Fang

    2012-10-01

    Full Text Available The metamaterial lens with DPS/DNS/DPS structure has been realized by using the two-dimensional (2D isotropic transmission line approach. We studied the vortexlike power flow at the interfaces of metamaterial lens and validated by the finite-difference time-domain (FDTD simulator. The computational results showing its different conditions near DPS/DNS and other kinds of interfaces are obtained by CST STUDIO SUITE at different frequencies, and demonstrate the intuitionistic power location at the metamaterial lens interfaces.

  20. Metamaterial-based transmit and receive system for whole-body magnetic resonance imaging at ultra-high magnetic fields.

    Science.gov (United States)

    Herrmann, Tim; Liebig, Thorsten; Mallow, Johannes; Bruns, Christian; Stadler, Jörg; Mylius, Judith; Brosch, Michael; Svedja, Jan Taro; Chen, Zhichao; Rennings, Andreas; Scheich, Henning; Plaumann, Markus; Hauser, Marcus J B; Bernarding, Johannes; Erni, Daniel

    2018-01-01

    Magnetic resonance imaging (MRI) at ultra-high fields (UHF), such as 7 T, provides an enhanced signal-to-noise ratio and has led to unprecedented high-resolution anatomic images and brain activation maps. Although a variety of radio frequency (RF) coil architectures have been developed for imaging at UHF conditions, they usually are specialized for small volumes of interests (VoI). So far, whole-body coil resonators are not available for commercial UHF human whole-body MRI systems. The goal of the present study was the development and validation of a transmit and receive system for large VoIs that operates at a 7 T human whole-body MRI system. A Metamaterial Ring Antenna System (MRAS) consisting of several ring antennas was developed, since it allows for the imaging of extended VoIs. Furthermore, the MRAS not only requires lower intensities of the irradiated RF energy, but also provides a more confined and focused injection of excitation energy on selected body parts. The MRAS consisted of several antennas with 50 cm inner diameter, 10 cm width and 0.5 cm depth. The position of the rings was freely adjustable. Conformal resonant right-/left-handed metamaterial was used for each ring antenna with two quadrature feeding ports for RF power. The system was successfully implemented and demonstrated with both a silicone oil and a water-NaCl-isopropanol phantom as well as in vivo by acquiring whole-body images of a crab-eating macaque. The potential for future neuroimaging applications was demonstrated by the acquired high-resolution anatomic images of the macaque's head. Phantom and in vivo measurements of crab-eating macaques provided high-resolution images with large VoIs up to 40 cm in xy-direction and 45 cm in z-direction. The results of this work demonstrate the feasibility of the MRAS system for UHF MRI as proof of principle. The MRAS shows a substantial potential for MR imaging of larger volumes at 7 T UHF. This new technique may provide new diagnostic potential

  1. Numerical calculation of spatially variant anisotropic metamaterials

    Science.gov (United States)

    Gulib, Asad Ullah Hil

    3D printing, or additive manufacturing, is rapidly evolving into a mainstream manufacturing technology that is creating new opportunities for electromagnetics and circuits. 3D printing permits circuits to fully utilize the third dimension allowing more functions in the same amount of space and allows the devices to have arbitrary form factors. 3D printing is letting us discover new physics that is not possible in standard 2D circuits and devices. However, evolving electromagnetics and circuits into three dimensions introduces some serious problems like thermal management, interference, and mutual coupling between the components which degrades performance and hurts signal integrity. Metamaterials are engineered composites that exhibit extreme electromagnetic properties and allow extraordinary control over electromagnetic fields. The EM Lab is developing spatially-variant anisotropic metamaterials (SVAMs) as a solution to mitigate mutual coupling between components. The concept of SVAMs is to electrically stretch the space between components to reduce mutual coupling. To do this, alternating layers of different dielectric must bisect adjacent components. However, the overall dielectric fill must also conform around dozens of electrical components and be smooth, continuous, and defect free. The research described here is the first prototype of an algorithm which generates a SVAM infill between all of the electrical components of a circuit in order to reduce the mutual coupling.

  2. Dispersion characteristics of a nonlinear elastic metamaterial

    Directory of Open Access Journals (Sweden)

    R. Khajehtourian

    2014-12-01

    Full Text Available We study wave dispersion in a one-dimensional nonlinear elastic metamaterial consisting of a thin rod with periodically attached local resonators. Our model is based on an exact finite-strain dispersion relation for a homogeneous solid, utilized in conjunction with the standard transfer matrix method for a periodic medium. The nonlinearity considered stems from large elastic deformation in the thin rod, whereas the metamaterial behavior is associated with the dynamics of the local resonators. We derive an approximate dispersion relation for this system and provide an analytical prediction of band-gap characteristics. The results demonstrate the effect of the nonlinearity on the characteristics of the band structure, including the size, location, and character of the band gaps. For example, large deformation alone may cause a pair of isolated Bragg-scattering and local-resonance band gaps to coalesce. We show that for a wave amplitude on the order of one-eighth of the unit cell size, the effect of the nonlinearity in the structure considered is no longer negligible when the unit-cell size is one-fourteenth of the wavelength or larger.

  3. Effective medium theory for anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2015-01-20

    Materials with anisotropic material parameters can be utilized to fabricate many fascinating devices, such as hyperlenses, metasolids, and one-way waveguides. In this study, we analyze the effects of geometric anisotropy on a two-dimensional metamaterial composed of a rectangular array of elliptic cylinders and derive an effective medium theory for such a metamaterial. We find that it is possible to obtain a closed-form analytical solution for the anisotropic effective medium parameters, provided the aspect ratio of the lattice and the eccentricity of the elliptic cylinder satisfy certain conditions. The derived effective medium theory not only recovers the well-known Maxwell-Garnett results in the quasi-static regime, but is also valid beyond the long-wavelength limit, where the wavelength in the host medium is comparable to the size of the lattice so that previous anisotropic effective medium theories fail. Such an advance greatly broadens the applicable realm of the effective medium theory and introduces many possibilities in the design of structures with desired anisotropic material characteristics. A real sample of a recently theoretically proposed anisotropic medium, with a near-zero index to control the flux, is achieved using the derived effective medium theory, and control of the electromagnetic waves in the sample is clearly demonstrated.

  4. Infrared Energy Harvesting for Optoplasmonics from Nanostructured Metamaterials

    Science.gov (United States)

    Forcherio, Gregory Thomas

    Metamaterials exhibit unique optical resonance characteristics which permit precise engineering of energy pathways within a device. The ability of plasmonic nanostructures to guide electromagnetism offers a platform to reduce global dependence on fossil fuels by harvesting waste heat, which comprises 60% of generated energy around the world. Plasmonic metamaterials were hypothesized to support an exchange of energy between resonance modes, enabling generation of higher energy photons from waste infrared energy. Infrared irradiation of a metamaterial at the Fano coupling lattice resonance was anticipated to re-emit as higher energy visible light at the plasmon resonance. Photonic signals from harvested thermal energy could be used to power wearable medical monitors or off-grid excursions, for example. This thesis developed the design, fabrication, and characterization methods to realize nanostructured metamaterials which permit resonance exchange for infrared energy harvesting applications.

  5. Sound reduction by metamaterial-based acoustic enclosure

    Directory of Open Access Journals (Sweden)

    Shanshan Yao

    2014-12-01

    Full Text Available In many practical systems, acoustic radiation control on noise sources contained within a finite volume by an acoustic enclosure is of great importance, but difficult to be accomplished at low frequencies due to the enhanced acoustic-structure interaction. In this work, we propose to use acoustic metamaterials as the enclosure to efficiently reduce sound radiation at their negative-mass frequencies. Based on a circularly-shaped metamaterial model, sound radiation properties by either central or eccentric sources are analyzed by numerical simulations for structured metamaterials. The parametric analyses demonstrate that the barrier thickness, the cavity size, the source type, and the eccentricity of the source have a profound effect on the sound reduction. It is found that increasing the thickness of the metamaterial barrier is an efficient approach to achieve large sound reduction over the negative-mass frequencies. These results are helpful in designing highly efficient acoustic enclosures for blockage of sound in low frequencies.

  6. Modelling, fabrication and characterisation of THz fractal meta-materials

    DEFF Research Database (Denmark)

    Xiao, S.; Zhou, L.; Malureanu, Radu

    2011-01-01

    We present theoretical predictions, fabrication procedure and characterisation results of fractal metamaterials for the THz frequency range. The characterisation results match well the predicted response thus validating both the fabrication procedure as well as the simulation one. Such systems show...

  7. A two-component NZRI metamaterial based rectangular cloak

    Directory of Open Access Journals (Sweden)

    Sikder Sunbeam Islam

    2015-10-01

    Full Text Available A new two-component, near zero refractive index (NZRI metamaterial is presented for electromagnetic rectangular cloaking operation in the microwave range. In the basic design a pi-shaped, metamaterial was developed and its characteristics were investigated for the two major axes (x and z-axis wave propagation through the material. For the z-axis wave propagation, it shows more than 2 GHz bandwidth and for the x-axis wave propagation; it exhibits more than 1 GHz bandwidth of NZRI property. The metamaterial was then utilized in designing a rectangular cloak where a metal cylinder was cloaked perfectly in the C-band area of microwave regime. The experimental result was provided for the metamaterial and the cloak and these results were compared with the simulated results. This is a novel and promising design for its two-component NZRI characteristics and rectangular cloaking operation in the electromagnetic paradigm.

  8. Formation of rarefaction waves in origami-based metamaterials.

    Science.gov (United States)

    Yasuda, H; Chong, C; Charalampidis, E G; Kevrekidis, P G; Yang, J

    2016-04-01

    We investigate the nonlinear wave dynamics of origami-based metamaterials composed of Tachi-Miura polyhedron (TMP) unit cells. These cells exhibit strain softening behavior under compression, which can be tuned by modifying their geometrical configurations or initial folded conditions. We assemble these TMP cells into a cluster of origami-based metamaterials, and we theoretically model and numerically analyze their wave transmission mechanism under external impact. Numerical simulations show that origami-based metamaterials can provide a prototypical platform for the formation of nonlinear coherent structures in the form of rarefaction waves, which feature a tensile wavefront upon the application of compression to the system. We also demonstrate the existence of numerically exact traveling rarefaction waves in an effective lumped-mass model. Origami-based metamaterials can be highly useful for mitigating shock waves, potentially enabling a wide variety of engineering applications.

  9. Conservation laws for perturbed solitons in optical metamaterials

    Science.gov (United States)

    Biswas, Anjan; Yaşar, Emrullah; Yıldırım, Yakup; Triki, Houria; Zhou, Qin; Moshokoa, Seithuti P.; Belic, Milivoj

    2018-03-01

    The conservation laws for the dynamics of soliton propagation through optical metamaterials are derived by the aid of Lie symmetry analysis. The proposed model will be studied with two forms of nonlinearity. They are Kerr law and parabolic law.

  10. Tunable VO{sub 2}/Au hyperbolic metamaterial

    Energy Technology Data Exchange (ETDEWEB)

    Prayakarao, S.; Noginov, M. A., E-mail: mnoginov@nsu.edu [Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States); Mendoza, B.; Devine, A. [Summer Research Program, Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States); Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14850 (United States); Kyaw, C. [Summer Research Program, Center for Materials Research, Norfolk State University, Norfolk, Virginia 23504 (United States); Dover, R. B. van [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14850 (United States); Liberman, V. [MIT LINCOLN Laboratory, 244 Wood Street, Lexington, Massachusetts 02420 (United States)

    2016-08-08

    Vanadium dioxide (VO{sub 2}) is known to have a semiconductor-to-metal phase transition at ∼68 °C. Therefore, it can be used as a tunable component of an active metamaterial. The lamellar metamaterial studied in this work is composed of subwavelength VO{sub 2} and Au layers and is designed to undergo a temperature controlled transition from the optical hyperbolic phase to the metallic phase. VO{sub 2} films and VO{sub 2}/Au lamellar metamaterial stacks have been fabricated and studied in electrical conductivity and optical (transmission and reflection) experiments. The observed temperature-dependent changes in the reflection and transmission spectra of the metamaterials and VO{sub 2} thin films are in a good qualitative agreement with theoretical predictions. The demonstrated optical hyperbolic-to-metallic phase transition is a unique physical phenomenon with the potential to enable advanced control of light-matter interactions.

  11. Active Metamaterial Based Ultrasonic Guided Wave Transducer System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — An active and tunable metamaterial phased array transducer for guided wave mode selection with high intensity per driving channel and with dramatically lower modal...

  12. Dissipative elastic metamaterial with a low-frequency passband

    Science.gov (United States)

    Liu, Yongquan; Yi, Jianlin; Li, Zheng; Su, Xianyue; Li, Wenlong; Negahban, Mehrdad

    2017-06-01

    We design and experimentally demonstrate a dissipative elastic metamaterial structure that functions as a bandpass filter with a low-frequency passband. The mechanism of dissipation in this structure is well described by a mass-spring-damper model that reveals that the imaginary part of the wavenumber is non-zero, even in the passband of dissipative metamaterials. This indicates that transmittance in this range can be low. A prototype for this viscoelastic metamaterial model is fabricated by 3D printing techniques using soft and hard acrylics as constituent materials. The transmittance of the printed metamaterial is measured and shows good agreement with theoretical predictions, demonstrating its potential in the design of compact waveguides, filters and other advanced devices for controlling mechanical waves.

  13. Dissipative elastic metamaterial with a low-frequency passband

    Directory of Open Access Journals (Sweden)

    Yongquan Liu

    2017-06-01

    Full Text Available We design and experimentally demonstrate a dissipative elastic metamaterial structure that functions as a bandpass filter with a low-frequency passband. The mechanism of dissipation in this structure is well described by a mass-spring-damper model that reveals that the imaginary part of the wavenumber is non-zero, even in the passband of dissipative metamaterials. This indicates that transmittance in this range can be low. A prototype for this viscoelastic metamaterial model is fabricated by 3D printing techniques using soft and hard acrylics as constituent materials. The transmittance of the printed metamaterial is measured and shows good agreement with theoretical predictions, demonstrating its potential in the design of compact waveguides, filters and other advanced devices for controlling mechanical waves.

  14. Engineering metamaterial absorbers from dense gold nanoparticle stacks

    Science.gov (United States)

    Hewlett, Sheldon; Mock, Adam

    2017-09-01

    Both ordered and disordered electromagnetic metamaterials have been shown to exhibit interesting and technologically relevant properties that would not be present in the constituent materials in their bulk form. Disordered metamaterials can be fabricated using low-cost and scalable fabrication approaches which are particularly advantageous at the nanoscale. This work shows how a solution-based deposition process can be leveraged to introduce quasi-ordering in disordered gold metamaterials to achieve 94% absorption over the visible spectrum. Full-wave electrodynamic simulations suggest that more advanced structures consistent with this fabrication approach could exhibit 98% average absorption over the entire solar spectrum. We envision this simple and cost-effective fabrication of highly absorbing disordered metamaterials to be of use for thermovoltaics and solar cells.

  15. Investigation of graphene-integrated tunable metamaterials in THz regime

    Science.gov (United States)

    Demir, S. Mahircan; Yüksek, Yahya; Sabah, Cumali

    2018-05-01

    A metallic fishnet metamaterial structure in sub-THz region is presented. The proposed structure is based on hexagonal resonators. Simulations have been performed by a 3D full-wave electromagnetic simulator and a negative refractive index has been observed at the frequency range between 0.55 and 0.70 THz with the help of the graphene layer. In order to observe the effect of the graphene layer, the metamaterial structure has been simulated and examined before and after graphene integration. Significant modification in the propagation properties has been observed after the graphene integration. Change in S-parameters with the size variation of hexagonal resonators and alteration in graphene thickness are also presented as a parametric study to show the tunability of the structure. Suitability of the metamaterial for sensor applications has been investigated. The proposed metamaterial structure is promising to be effectively used for tunability and sensor applications.

  16. Acoustic metamaterials for new two-dimensional sonic devices

    Energy Technology Data Exchange (ETDEWEB)

    Torrent, Daniel; Sanchez-Dehesa, Jose [Wave Phenomena Group, Department of Electronic Engineering, Polytechnic University of Valencia, C/Camino de Vera sn, E-46022 Valencia (Spain)

    2007-09-15

    It has been shown that two-dimensional arrays of rigid or fluidlike cylinders in a fluid or a gas define, in the limit of large wavelengths, a class of acoustic metamaterials whose effective parameters (sound velocity and density) can be tailored up to a certain limit. This work goes a step further by considering arrays of solid cylinders in which the elastic properties of cylinders are taken into account. We have also treated mixtures of two different elastic cylinders. It is shown that both effects broaden the range of acoustic parameters available for designing metamaterials. For example, it is predicted that metamaterials with perfect matching of impedance with air are now possible by using aerogel and rigid cylinders equally distributed in a square lattice. As a potential application of the proposed metamaterial, we present a gradient index lens for airborne sound (i.e. a sonic Wood lens) whose functionality is demonstrated by multiple scattering simulations.

  17. Metamaterial-Backed Conformal Antennas for Space Exploration

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this experiment is to demonstrate a successful X-band antenna array fabricated on a high-permittivity substrate together with bandgap metamaterials...

  18. Enhancement of the Purcell factor in multiperiodic hyperboliclike metamaterials

    DEFF Research Database (Denmark)

    Chebykin, A. V.; Babicheva, V. E.; Iorsh, I. V.

    2016-01-01

    Spontaneous emission enhancement is theoretically investigated in multiperiodic metal-dielectric multilayers (multiperiodic hyperboliclike metamaterials or photonic hypercrystals) where the unit cell consists of two layers of different dielectrics alternating with identical metallic layers. It is...

  19. Plasmonic Nanocone Arrays as Photoconductive and Photovoltaic Metamaterials

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Babicheva, Viktoriia; Evlyuknin, Andrey B.

    2014-01-01

    Photoconductive and photovolta ic properties of metamaterials comprising plasmonic nanocone arrays embedded in a semiconductor matrix are studied. Under uniform plane-wave illumination, directed photocurrent and electromotive force arise ne ar asymmetrically shaped nanocones. The resulting giant ...

  20. Three-dimensional metamaterials fabricated using Proton Beam Writing

    Energy Technology Data Exchange (ETDEWEB)

    Bettiol, A.A., E-mail: a.bettiol@nus.edu.sg [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, 2 Science Dr. 3, Singapore 117542 (Singapore); Turaga, S.P.; Yan, Y.; Vanga, S.K. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, 2 Science Dr. 3, Singapore 117542 (Singapore); Chiam, S.Y. [NUS High School for Maths and Science, 20 Clementi Avenue 1, Singapore 129957 (Singapore)

    2013-07-01

    Proton Beam Writing (PBW) is a direct write lithographic technique that has recently been applied to the fabrication of three dimensional metamaterials. In this work, we show that the unique capabilities of PBW, namely the ability to fabricate arrays of high resolution, high aspect ratio microstructures in polymer or replicated into metal, is well suited to metamaterials research. We have also developed a novel method for selectively electroless plating silver directly onto polymer structures that were fabricated using PBW. This method opens up new avenues for utilizing PBW for making metamaterials and other sub-wavelength metallic structures. Several potential applications of three dimensional metamaterials fabricated using PBW are discussed, including sensing and negative refractive index materials.

  1. CHIRAL WAVES IN A METAMATERIAL MEDIUM ONDAS QUIRALES EN UN MEDIO METAMATERIAL

    Directory of Open Access Journals (Sweden)

    Héctor Torres-Silva

    2008-11-01

    Full Text Available In this paper we study the anomalous refraction at the boundary of a metamaterial medium with strong chirality. The fact that for a time-harmonic monochromatic plane wave the direction of the Poynting vector is antiparallel with the direction of phase velocity, leads to exciting features that can be advantageous in the design of novel devices and components at microwaves frequencies.En este trabajo se estudia la refracción anómala en el borde de un medio metamaterial con fuerte quiralidad. El hecho de que para una onda monocromática el vector de Poynting es antiparalelo a la dirección de la velocidad de fase conduce a relevantes propiedades que pueden tener ventajas en el diseño de novedosos dispositivos y componentes a frecuencias de microondas.

  2. Electrically Small Resonators for Metamaterial and Microwave Circuit Design

    OpenAIRE

    Gil, Marta; Aznar, Francisco; Velez, Adolfo; Duran-Sindreu, Miguel; Selga, Jordi; Siso, Gerard; Bonache, Jordi; Martin, Ferran

    2010-01-01

    In this chapter, different kinds of resonant-type metamaterial transmission lines based on subwavelength resonators have been presented and studied. There are several types of resonators which allow their use in the implementation of this kind of artificial transmission lines and their small size is exploited in order to achieve device miniaturisation. Besides their small size, metamaterial transmission lines allow the control of their electrical characteristics, opening the door to very comp...

  3. Simulation of Zitterbewegung by modelling the Dirac equation in Metamaterials

    OpenAIRE

    Ahrens, Sven; Jiang, Jun; Sun, Yong; Zhu, Shi-Yao

    2015-01-01

    We develop a dynamic description of an effective Dirac theory in metamaterials, in which the wavefunction is modeled by the corresponding electric and magnetic field in the metamaterial. This electro-magnetic field can be probed in the experimental setup, which means that the wavefunction of the effective theory is directly accessible by measurement. Our model is based on a plane wave expansion, which ravels the identification of Dirac spinors with single-frequency excitations of the electro-...

  4. Evaluating the potential shielding properties of periodic metamaterial slabs

    OpenAIRE

    SEETHARAMDOO, D; BERBINEAU, M; TAROT, A; MAHDJOUBI, K

    2009-01-01

    Metamaterials can prove to be good candidates for shields in EMC applications where weight reduction is a challenge. Indeed metamaterial slabs can provide the same reflective properties as conventional metallic screens but with a lower density and reduced weight. Another advantage is that they can be tailored to exhibit required frequency-selective properties. However, their performance in terms of shielding performance has yet to be evaluated. In this paper, a method to evaluate the shieldin...

  5. Enhancement of critical temperature in fractal metamaterial superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Smolyaninov, Igor I., E-mail: smoly@umd.edu [Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742 (United States); Smolyaninova, Vera N. [Department of Physics Astronomy and Geosciences, Towson University, 8000 York Road, Towson, MD 21252 (United States)

    2017-04-15

    Fractal metamaterial superconductor geometry has been suggested and analyzed based on the recently developed theoretical description of critical temperature increase in epsilon near zero (ENZ) metamaterial superconductors. Considerable enhancement of critical temperature has been predicted in such materials due to appearance of large number of additional poles in the inverse dielectric response function of the fractal. Our results agree with the recent observation (Fratini et al. Nature 466, 841 (2010)) that fractal defect structure promotes superconductivity.

  6. Electrical dynamic modulation of THz radiation based on superconducting metamaterials

    Science.gov (United States)

    Li, Chun; Wu, Jingbo; Jiang, Shoulu; Su, Runfeng; Zhang, Caihong; Jiang, Chengtao; Zhou, Gaochao; Jin, Biaobing; Kang, Lin; Xu, Weiwei; Chen, Jian; Wu, Peiheng

    2017-08-01

    We demonstrate an electrically tunable superconducting metamaterial capable of modulating terahertz waves dynamically. The device is based on electromagnetically induced transparency-like metamaterials, and the maximum modulation depth reaches 79.8% in the transmission window. Controlled by an electrical sinusoidal signal, such a device could achieve a modulation speed of approximately 1 MHz. The superior property and simplicity of design make this device promising for the development of high performance THz systems.

  7. Transformation electromagnetics and metamaterials fundamental principles and applications

    CERN Document Server

    Werner, Douglas H

    2013-01-01

    Transformation electromagnetics is a systematic design technique for optical and electromagnetic devices that enables novel wave-material interaction properties. The associated metamaterials technology for designing and realizing optical and electromagnetic devices can control the behavior of light and electromagnetic waves in ways that have not been conventionally possible. The technique is credited with numerous novel device designs, most notably the invisibility cloaks, perfect lenses and a host of other remarkable devices.Transformation Electromagnetics and Metamaterials: Fundamental Princ

  8. Bloch-mode analysis for retrieving effective parameters of metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, Sangwoo; Sukhorukov, Andrey A.

    2012-01-01

    We introduce an approach for retrieving effective parameters of metamaterials based on the Bloch-mode analysis of quasiperiodic composite structures. We demonstrate that, in the case of single-mode propagation, a complex effective refractive index can be assigned to the structure, being restored...... that this approach can be useful for retrieval of both material and wave effective parameters of a broad range of metamaterials....

  9. Preface to Special Topic: Acoustic Metamaterials and Metasurfaces

    Science.gov (United States)

    Assouar, Badreddine

    2018-03-01

    The advent of acoustic metamaterials in the beginning of 2000s and very recently of acoustic metasurfaces has created tremendous excitement and efforts in the field of materials science and physics by introducing and building real transformative research and dealing with unprecedented physics and applications. The acoustic/elastic metamaterials and metasurfaces, which can simply be described as designed artificial materials with unusual physical properties, form the core of the present Special Topic published by the Journal of Applied Physics.

  10. Acoustic wave propagation and stochastic effects in metamaterial absorbers

    DEFF Research Database (Denmark)

    Christensen, Johan; Willatzen, Morten

    2014-01-01

    We show how stochastic variations of the effective parameters of anisotropic structured metamaterials can lead to increased absorption of sound. For this, we derive an analytical model based on the Bourret approximation and illustrate the immediate connection between material disorder and attenua......We show how stochastic variations of the effective parameters of anisotropic structured metamaterials can lead to increased absorption of sound. For this, we derive an analytical model based on the Bourret approximation and illustrate the immediate connection between material disorder...

  11. Flexible metamaterial absorbers for stealth applications at terahertz frequencies

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Strikwerda, Andrew; Fan, K.

    2012-01-01

    We have wrapped metallic cylinders with strongly absorbing metamaterials. These resonant structures, which are patterned on flexible substrates, smoothly coat the cylinder and give it an electromagnetic response designed to minimize its radar cross section. We compare the normal-incidence, small...... frequency of 0.87 THz. In addition we discuss the effect of finite sample dimensions and the spatial dependence of the reflection spectrum of the metamaterial. (C)2011 Optical Society of America...

  12. Properties of Sub-wavelength Resonances in Metamaterial Cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Clausen, N.C.J.; Pedersen, R.R.

    2008-01-01

    The analytical solution for the canonical configuration with electric line source illumination of concentric metamaterial cylinders is employed to study the properties of the observed sub-wavelength resonances. The near- and far-field distributions, the frequency and geometry bandwidths, and the ......, and the line source impedance are investigated for varying electromagnetic and geometrical parameters. The results of this study are of importance for metamaterial-based miniaturization of antennas....

  13. Effective Surface Conductivity Approach for Graphene Metamaterials Based Terahertz Devices

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim

    2013-01-01

    We propose a description of graphene metamaterials properties through the effective surface conductivity. On the example of tunable absorber we demonstrate that this approach allows for fast and efficient design of functional terahertz devices.......We propose a description of graphene metamaterials properties through the effective surface conductivity. On the example of tunable absorber we demonstrate that this approach allows for fast and efficient design of functional terahertz devices....

  14. Manipulating electromagnetic waves with metamaterials: Concept and microwave realizations

    International Nuclear Information System (INIS)

    He Qiong; Xiao Shi-Yi; Li Xin; Song Zheng-Yong; Sun Wu-Jiong; Zhou Lei; Sun Shu-Lin

    2014-01-01

    Our recent efforts in manipulating electromagnetic (EM) waves using metamaterials (MTMs) are reviewed with emphasis on 1) manipulating wave polarization and transporting properties using homogeneous MTMs, 2) manipulating surface-wave properties using plasmonic MTMs, and 3) bridging propagating and surface waves using inhomogeneous meta-surfaces. For all these topics, we first illustrate the physical concepts and then present several typical practical realizations and applications in the microwave regime. (topical review - plasmonics and metamaterials)

  15. Metamaterial 3D Gain Nanostructures Fabricated Using Direct Laser Writing

    Science.gov (United States)

    2015-07-11

    AFRL-AFOSR-UK-TR-2015-0033 Metamaterial 3D Gain Nanostructures Fabricated Using Direct Laser Writing Maria Farsari...abricated Direct Laser Writing 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA8655-13-1-3048 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Maria Farsari 5d...Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39-18   1 Metamaterial 3D Gain Nanostructures Fabricated Using Direct Laser Writing EOARD

  16. Metamaterial apertures for coherent computational imaging on the physical layer.

    Science.gov (United States)

    Lipworth, Guy; Mrozack, Alex; Hunt, John; Marks, Daniel L; Driscoll, Tom; Brady, David; Smith, David R

    2013-08-01

    We introduce the concept of a metamaterial aperture, in which an underlying reference mode interacts with a designed metamaterial surface to produce a series of complex field patterns. The resonant frequencies of the metamaterial elements are randomly distributed over a large bandwidth (18-26 GHz), such that the aperture produces a rapidly varying sequence of field patterns as a function of the input frequency. As the frequency of operation is scanned, different subsets of metamaterial elements become active, in turn varying the field patterns at the scene. Scene information can thus be indexed by frequency, with the overall effectiveness of the imaging scheme tied to the diversity of the generated field patterns. As the quality (Q-) factor of the metamaterial resonators increases, the number of distinct field patterns that can be generated increases-improving scene estimation. In this work we provide the foundation for computational imaging with metamaterial apertures based on frequency diversity, and establish that for resonators with physically relevant Q-factors, there are potentially enough distinct measurements of a typical scene within a reasonable bandwidth to achieve diffraction-limited reconstructions of physical scenes.

  17. Harnessing the metal-insulator transition for tunable metamaterials

    Science.gov (United States)

    Charipar, Nicholas A.; Charipar, Kristin M.; Kim, Heungsoo; Bingham, Nicholas S.; Suess, Ryan J.; Mathews, Scott A.; Auyeung, Raymond C. Y.; Piqué, Alberto

    2017-08-01

    The control of light-matter interaction through the use of subwavelength structures known as metamaterials has facilitated the ability to control electromagnetic radiation in ways not previously achievable. A plethora of passive metamaterials as well as examples of active or tunable metamaterials have been realized in recent years. However, the development of tunable metamaterials is still met with challenges due to lack of materials choices. To this end, materials that exhibit a metal-insulator transition are being explored as the active element for future metamaterials because of their characteristic abrupt change in electrical conductivity across their phase transition. The fast switching times (▵t properties associated with thin film metal-insulator transition materials are strongly dependent on the growth conditions. For this work, we have studied how growth conditions (such as gas partial pressure) influence the metalinsulator transition in VO2 thin films made by pulsed laser deposition. In addition, strain engineering during the growth process has been investigated as a method to tune the metal-insulator transition temperature. Examples of both the optical and electrical transient dynamics facilitating the metal-insulator transition will be presented together with specific examples of thin film metamaterial devices.

  18. Thermally tunable broadband terahertz metamaterials with negative refractive index

    Science.gov (United States)

    Li, Weili; Meng, Qinglong; Huang, Renshuai; Zhong, Zheqiang; Zhang, Bin

    2018-04-01

    A thermally tunable broadband metamaterials with negative refractive index (NRI) is investigated in terahertz (THz) region theoretically. The metamaterials is designed by fabricating two stand-up opposite L shape metallic structures on fused quartz substrate, and the indium antimonide (InSb) is filled in the bottom gap of the two L shape structures. The tunability is attributed to the InSb because the InSb can changes the capacitance of the gap area by adjusting the temperature. The transmission characteristics and the retrieved electromagnetic parameters of the metamaterials are analyzed. Results indicate that the resonant frequency and amplitude modulation of the metamaterials can be tuned continuously in broadband range (about 0.62 THz), and the phase modulation from - 2 to 3 rad is also achieved within broadband range (about 0.8 THz). In addition, the metamaterials shows dual-band NRI behaviors at 0 . 4- 0 . 9 THz and 1 . 06- 1 . 15 THz when the temperature increases to 400 K. The wedge-shaped prism simulations are implemented to verify the NRI characteristics and indicate that the NRI of the metamaterials can be achieved.

  19. Hierarchical ferroelectric and ferrotoroidic polarizations coexistent in nano-metamaterials.

    Science.gov (United States)

    Shimada, Takahiro; Lich, Le Van; Nagano, Koyo; Wang, Jie; Kitamura, Takayuki

    2015-10-01

    Tailoring materials to obtain unique, or significantly enhanced material properties through rationally designed structures rather than chemical constituents is principle of metamaterial concept, which leads to the realization of remarkable optical and mechanical properties. Inspired by the recent progress in electromagnetic and mechanical metamaterials, here we introduce the concept of ferroelectric nano-metamaterials, and demonstrate through an experiment in silico with hierarchical nanostructures of ferroelectrics using sophisticated real-space phase-field techniques. This new concept enables variety of unusual and complex yet controllable domain patterns to be achieved, where the coexistence between hierarchical ferroelectric and ferrotoroidic polarizations establishes a new benchmark for exploration of complexity in spontaneous polarization ordering. The concept opens a novel route to effectively tailor domain configurations through the control of internal structure, facilitating access to stabilization and control of complex domain patterns that provide high potential for novel functionalities. A key design parameter to achieve such complex patterns is explored based on the parity of junctions that connect constituent nanostructures. We further highlight the variety of additional functionalities that are potentially obtained from ferroelectric nano-metamaterials, and provide promising perspectives for novel multifunctional devices. This study proposes an entirely new discipline of ferroelectric nano-metamaterials, further driving advances in metamaterials research.

  20. Auxetic-like metamaterials as novel earthquake protections

    Directory of Open Access Journals (Sweden)

    Ungureanu Bogdan

    2015-01-01

    Full Text Available We propose that wave propagation through a class of mechanical metamaterials opens unprecedented avenues in seismic wave protection based on spectral properties of auxetic-like metamaterials. The elastic parameters of these metamaterials like the bulk and shear moduli, the mass density, and even the Poisson ratio, can exhibit negative values in elastic stop bands. We show here that the propagation of seismic waves with frequencies ranging from 1 Hz to 40 Hz can be influenced by a decameter scale version of auxetic-like metamaterials buried in the soil, with the combined effects of impedance mismatch, local resonances and Bragg stop bands. More precisely, we numerically examine and illustrate the markedly different behaviors between the propagation of seismic waves through a homogeneous isotropic elastic medium (concrete and an auxetic-like metamaterial plate consisting of 43 cells (40 m × 40 m × 40 m, utilized here as a foundation of a building one would like to protect from seismic site effects. This novel class of seismic metamaterials opens band gaps at frequencies compatible with seismic waves when they are designed appropriately, what makes them interesting candidates for seismic isolation structures.

  1. Hierarchical ferroelectric and ferrotoroidic polarizations coexistent in nano-metamaterials

    Science.gov (United States)

    Shimada, Takahiro; Lich, Le Van; Nagano, Koyo; Wang, Jie; Kitamura, Takayuki

    2015-10-01

    Tailoring materials to obtain unique, or significantly enhanced material properties through rationally designed structures rather than chemical constituents is principle of metamaterial concept, which leads to the realization of remarkable optical and mechanical properties. Inspired by the recent progress in electromagnetic and mechanical metamaterials, here we introduce the concept of ferroelectric nano-metamaterials, and demonstrate through an experiment in silico with hierarchical nanostructures of ferroelectrics using sophisticated real-space phase-field techniques. This new concept enables variety of unusual and complex yet controllable domain patterns to be achieved, where the coexistence between hierarchical ferroelectric and ferrotoroidic polarizations establishes a new benchmark for exploration of complexity in spontaneous polarization ordering. The concept opens a novel route to effectively tailor domain configurations through the control of internal structure, facilitating access to stabilization and control of complex domain patterns that provide high potential for novel functionalities. A key design parameter to achieve such complex patterns is explored based on the parity of junctions that connect constituent nanostructures. We further highlight the variety of additional functionalities that are potentially obtained from ferroelectric nano-metamaterials, and provide promising perspectives for novel multifunctional devices. This study proposes an entirely new discipline of ferroelectric nano-metamaterials, further driving advances in metamaterials research.

  2. Subwavelength optics with hyperbolic metamaterials: Waveguides, scattering, and optical topological transitions

    DEFF Research Database (Denmark)

    Ishii, Satoshi; Babicheva, Viktoriia E.; Shalaginov, Mikhail Y.

    2016-01-01

    Hyperbolic metamaterials possess unique optical properties owing to their hyperbolic dispersion. As hyperbolic metamaterials can be constructed just from periodic multilayers of metals and dielectrics, they have attracted considerable attention in the nanophotonics community. Here, we review some...

  3. Terahertz polarization converter based on all-dielectric high birefringence metamaterial with elliptical air holes

    KAUST Repository

    Zi, Jianchen

    2018-02-15

    Metamaterials have been widely applied in the polarization conversion of terahertz (THz) waves. However, common plasmonic metamaterials usually work as reflective devices and have low transmissions. All-dielectric metamaterials can overcome these shortcomings. An all-dielectric metamaterial based on silicon with elliptical air holes is reported to achieve high artificial birefringence at THz frequencies. Simulations show that with appropriate structural parameters the birefringence of the dielectric metamaterial can remain flat and is above 0.7 within a broad band. Moreover, the metamaterial can be designed as a broadband quarter wave plate. A sample metamaterial was fabricated and tested to prove the validity of the simulations, and the sample could work as a quarter wave plate at 1.76 THz. The all-dielectric metamaterial that we proposed is of great significance for high performance THz polarization converters.

  4. Experimental demonstration of a metal-dielectric metamaterial refractive index sensor

    Science.gov (United States)

    Li, Shengyong; Ai, Xiaochuan; Wu, Ronghua; Chen, Jiajun

    2018-03-01

    A metamaterial equipment is designed and experimental verified in the near-infrared with two reflectivity dips. The metamaterial equipment shows independent of polarization. Simulated results indicate that the reflectivity dip is excited by the coupling of localized surface plasmon (LSP) modes. The metamaterial equipment can work as a refractive index detection sensor with high figure of merit (FOM) value. This proposed metamaterial sensor can be applied in detecting different biochemical liquid.

  5. All-semiconductor metamaterial with negative refraction in the near-infrared

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Liu, Jingjing; Kildishev, Alexander V.

    2012-01-01

    When heavily doped, semiconductors such as ZnO can exhibit metallic properties thus becoming versatile building blocks for optical metamaterials. Here, we design and fabricate an all-semiconductor metamaterial and demonstrate negative refraction in the near-infrared region.......When heavily doped, semiconductors such as ZnO can exhibit metallic properties thus becoming versatile building blocks for optical metamaterials. Here, we design and fabricate an all-semiconductor metamaterial and demonstrate negative refraction in the near-infrared region....

  6. Geared Topological Metamaterials with Tunable Mechanical Stability

    Directory of Open Access Journals (Sweden)

    Anne S. Meeussen

    2016-11-01

    Full Text Available The classification of materials into insulators and conductors has been shaken up by the discovery of topological insulators that conduct robustly at the edge but not in the bulk. In mechanics, designating a material as insulating or conducting amounts to asking if it is rigid or floppy. Although mechanical structures that display topological floppy modes have been proposed, they are all vulnerable to global collapse. Here, we design and build mechanical metamaterials that are stable and yet capable of harboring protected edge and bulk modes, analogous to those in electronic topological insulators and Weyl semimetals. To do so, we exploit gear assemblies that, unlike point masses connected by springs, incorporate both translational and rotational degrees of freedom. Global structural stability is achieved by eliminating geometrical frustration of collective gear rotations extending through the assembly. The topological robustness of the mechanical modes makes them appealing across scales from engineered macrostructures to networks of toothed microrotors of potential use in micromachines.

  7. Metamaterial-Enhanced Nonlinear Terahertz Spectroscopy

    Directory of Open Access Journals (Sweden)

    Zhang X.

    2013-03-01

    Full Text Available We demonstrate large nonlinear terahertz responses in the gaps of metamaterial split ring resonators in several materials and use nonlinear THz transmission and THz-pump/THz-probe spectroscopy to study the nonlinear responses and dynamics. We use the field enhancement in the SRR gaps to initiate high-field phenomena at lower incident fields. In vanadium dioxide, we drive the insulator-to-metal phase transition with high-field THz radiation. The film conductivity increases by over two orders of magnitude and the phase transition occurs on a several picosecond timescale. In gallium arsenide, we observe high-field transport phenomena, including mobility saturation and impact ionization. The carrier density increases by up to ten orders of magnitude at high fields. At the highest fields, we demonstrate THz-induced damage in both vanadium dioxide and gallium arsenide.

  8. Ultrafast Coherent Absorption in Diamond Metamaterials.

    Science.gov (United States)

    Karvounis, Artemios; Nalla, Venkatram; MacDonald, Kevin F; Zheludev, Nikolay I

    2018-02-27

    Diamond is introduced as a material platform for visible/near-infrared photonic metamaterials, with a nanostructured polycrystalline diamond metasurface only 170 nm thick providing an experimental demonstration of coherent light-by-light modulation at few-optical-cycle (6 fs) pulse durations. "Coherent control" of absorption in planar (subwavelength-thickness) materials has emerged recently as a mechanism for high-contrast all-optical gating, with a speed of response that is limited only by the spectral width of the absorption line. It is shown here that a free-standing diamond membrane structured by focused ion beam milling can provide strong, spectrally near-flat absorption over a visible to near-infrared wavelength range that is wide enough (wider than is characteristically achievable in plasmonic metal metasurfaces) to facilitate coherent modulation of ultrashort optical pulses comprising only a few oscillations of electromagnetic field. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Metamaterial Electromagnetic Superabsorber with Arbitrary Geometries

    Directory of Open Access Journals (Sweden)

    Jingjing Yang

    2010-06-01

    Full Text Available The electromagnetic superabsorber that has larger absorption cross section than its real size may be a novel photothermal device with improved solar energy conversion rates. Based on a transformation optical approach, the material parameters for a two-dimensional (2D metamaterial-assisted electromagnetic superabsorber with arbitrary geometries are derived and validated by numerical simulation. We find that for the given geometry size, the absorption cross section of the superabsorber using nonlinear transformation is larger than that using linear transformation. These transformations can also be specialized to the designing the N-sided regular polygonal superabsorber just by changing the contour equation. All theoretical and numerical results validate the material parameters for the 2D electromagnetic superabsorber we have developed.

  10. Active control of chirality in nonlinear metamaterials

    International Nuclear Information System (INIS)

    Zhu, Yu; Chai, Zhen; Yang, Hong; Hu, Xiaoyong; Gong, Qihuang

    2015-01-01

    An all-optical tunabe chirality is realized in a photonic metamaterial, the metamolecule of which consists of a nonlinear nano-Au:polycrystalline indium-tin oxide layer sandwiched between two L-shaped gold nano-antennas twisted 90° with each other. The maximum circular dichroism reached 30%. Under excitation of a 40 kW/cm 2 weak pump light, the peak in the circular dichroism shifts 45 nm in the short-wavelength direction. An ultrafast response time of 35 ps is maintained. This work not only opens up the possibility for the realization of ultralow-power and ultrafast all-optical tunable chirality but also offers a way to construct ultrahigh-speed on-chip biochemical sensors

  11. Self-Induced Torque in Hyperbolic Metamaterials

    Science.gov (United States)

    Ginzburg, Pavel; Krasavin, Alexey V.; Poddubny, Alexander N.; Belov, Pavel A.; Kivshar, Yuri S.; Zayats, Anatoly V.

    2013-07-01

    Optical forces constitute a fundamental phenomenon important in various fields of science, from astronomy to biology. Generally, intense external radiation sources are required to achieve measurable effects suitable for applications. Here we demonstrate that quantum emitters placed in a homogeneous anisotropic medium induce self-torques, aligning themselves in the well-defined direction determined by an anisotropy, in order to maximize their radiation efficiency. We develop a universal quantum-mechanical theory of self-induced torques acting on an emitter placed in a material environment. The theoretical framework is based on the radiation reaction approach utilizing the rigorous Langevin local quantization of electromagnetic excitations. We show more than 2 orders of magnitude enhancement of the self-torque by an anisotropic metamaterial with hyperbolic dispersion, having negative ratio of permittivity tensor components, in comparison with conventional anisotropic crystals with the highest naturally available anisotropy.

  12. Investigations into homogenization of electromagnetic metamaterials

    DEFF Research Database (Denmark)

    Clausen, Niels Christian Jerichau

    This dissertation encompasses homogenization methods, with a special interest into their applications to metamaterial homogenization. The first method studied is the Floquet-Bloch method, that is based on the assumption of a material being infinite periodic. Its field can then be expanded in terms...... stack.The second method is analogous to the Floquet-Bloch method, with that difference, that it treats finite structures. A finite structure cannot strictly be expanded in spatial harmonics, but the field can be Fourier transformed, and expanded with a set of sinc basis functions, constituting a set...... of pseudo spatial harmonics. From expressions of the exact field in the 1D Bragg stack, the Fourier transform is computed, and a numerical inversion is performed to determine the relative weight of the sinc bassis functions.The third method, the so-called Nicolson-Ross-Weir (NRW) method, is based...

  13. Dispersion engineering in metamaterials and metasurfaces

    Science.gov (United States)

    Li, Xiong; Pu, Mingbo; Ma, Xiaoliang; Guo, Yinghui; Gao, Ping; Luo, Xiangang

    2018-02-01

    Dispersion engineering is essential for spectral utilization in electromagnetic systems. However, it is difficult to manage the dispersions in both natural materials and traditional electromagnetic waveguides since they are tightly related to fine structures of atoms, molecules and causality. The emergence of metamaterials and metasurfaces, which are made of subwavelength inclusions offers tremendous freedom to manipulate the electromagnetic parameters of materials and modes. Here, we review the basic principles, practical applications and recent advancements of the dispersion engineering in metadevices. The contributions of dispersion management in metadevice-based super-resolution imaging/nanolithography systems, planar functional devices, as well as the broadband perfect absorbers/polarization converters are discussed in depth. The challenges faced by this field as well as future developing trends are also presented in the conclusions.

  14. Metamaterial-Inspired Efficient Electrically Small Antenna

    DEFF Research Database (Denmark)

    Erentok, Aycan; Ziolkowski, R. W.

    2008-01-01

    Planar two-dimensional (2D) and volumetric three-dimensional (3D) metamaterial-inspired efficient electrically-small antennas that are easy to design; are easy and inexpensive to build; and are easy to test; are reported, i.e., the EZ antenna systems. The proposed 2D and 3D electrical- and magnetic......-based EZ antennas are shown to be naturally matched to a 50 source, i.e., without the introduction of a matching network. It is demonstrated numerically that these EZ antennas have high radiation efficiencies with very good impedance matching between the source and the antenna and, hence, that they have...... high overall efficiencies. The reported 2D and 3D EZ antenna designs are linearly scalable to a wide range of frequencies and yet maintain their easy-to-build characteristics. Several versions of the 2D EZ antennas were fabricated and tested. The measurement results confirm the performance predictions...

  15. Ultrathin microwave metamaterial absorber utilizing embedded resistors

    Science.gov (United States)

    Kim, Young Ju; Hwang, Ji Sub; Yoo, Young Joon; Khuyen, Bui Xuan; Rhee, Joo Yull; Chen, Xianfeng; Lee, YoungPak

    2017-10-01

    We numerically and experimentally studied an ultrathin and broadband perfect absorber by enhancing the bandwidth with embedded resistors into the metamaterial structure, which is easy to fabricate in order to lower the Q-factor and by using multiple resonances with the patches of different sizes. We analyze the absorption mechanism in terms of the impedance matching with the free space and through the distribution of surface current at each resonance frequency. The magnetic field, induced by the antiparallel surface currents, is formed strongly in the direction opposite to the incident electromagnetic wave, to cancel the incident wave, leading to the perfect absorption. The corresponding experimental absorption was found to be higher than 97% in 0.88-3.15 GHz. The agreement between measurement and simulation was good. The aspects of our proposed structure can be applied to future electronic devices, for example, advanced noise-suppression sheets in the microwave regime.

  16. Applicability of point-dipoles approximation to all-dielectric metamaterials

    DEFF Research Database (Denmark)

    Kuznetsova, S. M.; Andryieuski, Andrei; Lavrinenko, Andrei

    2015-01-01

    All-dielectric metamaterials consisting of high-dielectric inclusions in a low-dielectric matrix are considered as a low-loss alternative to resonant metal-based metamaterials. In this paper we investigate the applicability of the point electric and magnetic dipoles approximation to dielectric meta......-atoms on the example of a dielectric ring metamaterial. Despite the large electrical size of high-dielectric meta-atoms, the dipole approximation allows for accurate prediction of the metamaterials properties for the rings with diameters up to approximate to 0.8 of the lattice constant. The results provide important...... guidelines for design and optimization of all-dielectric metamaterials....

  17. Comparison of electromagnetically induced transparency between silver, gold, and aluminum metamaterials at visible wavelengths.

    Science.gov (United States)

    Hokari, Ryohei; Kanamori, Yoshiaki; Hane, Kazuhiro

    2014-02-10

    Electromagnetically induced transparency (EIT)-like effects in silver, gold, and aluminum metamaterials consisting of dipole resonators and quadrupole resonators were demonstrated at visible wavelengths. Optical characteristics of the metamaterials could be controlled by the gap distance between the two resonators. EIT-like effects were observed at wavelengths between 603 and 789 nm, 654 and 834 nm, and 462 and 693 nm for the silver, gold, and aluminum EIT metamaterials, respectively. At wavelengths longer than around 650 nm, the silver metamaterials had better EIT-like features. At wavelengths shorter than around 650 nm, on the other hand, the aluminum metamaterials showed promising EIT-like results.

  18. Controlling Energy Radiations of Electromagnetic Waves via Frequency Coding Metamaterials.

    Science.gov (United States)

    Wu, Haotian; Liu, Shuo; Wan, Xiang; Zhang, Lei; Wang, Dan; Li, Lianlin; Cui, Tie Jun

    2017-09-01

    Metamaterials are artificial structures composed of subwavelength unit cells to control electromagnetic (EM) waves. The spatial coding representation of metamaterial has the ability to describe the material in a digital way. The spatial coding metamaterials are typically constructed by unit cells that have similar shapes with fixed functionality. Here, the concept of frequency coding metamaterial is proposed, which achieves different controls of EM energy radiations with a fixed spatial coding pattern when the frequency changes. In this case, not only different phase responses of the unit cells are considered, but also different phase sensitivities are also required. Due to different frequency sensitivities of unit cells, two units with the same phase response at the initial frequency may have different phase responses at higher frequency. To describe the frequency coding property of unit cell, digitalized frequency sensitivity is proposed, in which the units are encoded with digits "0" and "1" to represent the low and high phase sensitivities, respectively. By this merit, two degrees of freedom, spatial coding and frequency coding, are obtained to control the EM energy radiations by a new class of frequency-spatial coding metamaterials. The above concepts and physical phenomena are confirmed by numerical simulations and experiments.

  19. Predicting nonlinear properties of metamaterials from the linear response.

    Science.gov (United States)

    O'Brien, Kevin; Suchowski, Haim; Rho, Junsuk; Salandrino, Alessandro; Kante, Boubacar; Yin, Xiaobo; Zhang, Xiang

    2015-04-01

    The discovery of optical second harmonic generation in 1961 started modern nonlinear optics. Soon after, R. C. Miller found empirically that the nonlinear susceptibility could be predicted from the linear susceptibilities. This important relation, known as Miller's Rule, allows a rapid determination of nonlinear susceptibilities from linear properties. In recent years, metamaterials, artificial materials that exhibit intriguing linear optical properties not found in natural materials, have shown novel nonlinear properties such as phase-mismatch-free nonlinear generation, new quasi-phase matching capabilities and large nonlinear susceptibilities. However, the understanding of nonlinear metamaterials is still in its infancy, with no general conclusion on the relationship between linear and nonlinear properties. The key question is then whether one can determine the nonlinear behaviour of these artificial materials from their exotic linear behaviour. Here, we show that the nonlinear oscillator model does not apply in general to nonlinear metamaterials. We show, instead, that it is possible to predict the relative nonlinear susceptibility of large classes of metamaterials using a more comprehensive nonlinear scattering theory, which allows efficient design of metamaterials with strong nonlinearity for important applications such as coherent Raman sensing, entangled photon generation and frequency conversion.

  20. Permanent magnetic ferrite based power-tunable metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guanqiao; Lan, Chuwen [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Gao, Rui [High Temperature Thermochemistry Laboratory, Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0C5 (Canada); Zhou, Ji, E-mail: zhouji@tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-08-15

    Highlights: • Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated. • It is observed that resonant frequency of the array shifts upon altering the output power. • This kind of power-tunable behavior is due to the temperature rise as a result of FMR-induced heat buildup. • This work offers a practical idea to tune ferrite metamaterials besides magneto-tunability and thermal-tunability. - Abstract: Power-tunable metamaterials based on barium permanent magnetic ferrite have been proposed and fabricated in this research. Scattering parameter measurements confirm a shift in resonant frequency in correlation to changes in incident electromagnetic power within microwave frequency band. The tunable phenomenon represented by a blue-shift in transmission spectra in the metamaterials array can be attributed to a decrease in saturation magnetization resulting from FMR-induced temperature elevation upon resonant conditions. This power-dependent behavior offers a simple and practical route towards dynamically fine-tunable ferrite metamaterials.