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Sample records for metamaterials enables lossless

  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. Lossless acoustic half-bipolar cylindrical cloak with negative-index metamaterial

    Science.gov (United States)

    Lee, Yong Y.; Ahn, Doyeol

    2018-05-01

    A lossless acoustic half-bipolar cylindrical cloak that has an exposed bottom is considered. Here, we show that a cloak that includes a complementary region including a negative-index medium inside of the cloaking shell works in the illumination direction independently even in the presence of the exposed bottom of the structure. This is due to the fact that the phase velocity of the wave in the normal direction can be cancelled in the presence of a boundary containing a negative-index medium that reduces scattering significantly.

  3. Arbitrary beam control using passive lossless metasurfaces enabled by orthogonally polarized custom surface waves

    Science.gov (United States)

    Kwon, Do-Hoon; Tretyakov, Sergei A.

    2018-01-01

    For passive, lossless impenetrable metasurfaces, a design technique for arbitrary beam control of receiving, guiding, and launching is presented. Arbitrary control is enabled by a custom surface wave in an orthogonal polarization such that its addition to the incident (input) and the desired scattered (output) fields is supported by a reactive surface impedance everywhere on the reflecting surface. Such a custom surface wave (SW) takes the form of an evanescent wave propagating along the surface with a spatially varying envelope. A growing SW appears when an illuminating beam is received. The SW amplitude stays constant when power is guided along the surface. The amplitude diminishes as a propagating wave (PW) is launched from the surface as a leaky wave. The resulting reactive tensor impedance profile may be realized as an array of anisotropic metallic resonators printed on a grounded dielectric substrate. Illustrative design examples of a Gaussian beam translator-reflector, a probe-fed beam launcher, and a near-field focusing lens are provided.

  4. ChIPWig: a random access-enabling lossless and lossy compression method for ChIP-seq data.

    Science.gov (United States)

    Ravanmehr, Vida; Kim, Minji; Wang, Zhiying; Milenkovic, Olgica

    2018-03-15

    Chromatin immunoprecipitation sequencing (ChIP-seq) experiments are inexpensive and time-efficient, and result in massive datasets that introduce significant storage and maintenance challenges. To address the resulting Big Data problems, we propose a lossless and lossy compression framework specifically designed for ChIP-seq Wig data, termed ChIPWig. ChIPWig enables random access, summary statistics lookups and it is based on the asymptotic theory of optimal point density design for nonuniform quantizers. We tested the ChIPWig compressor on 10 ChIP-seq datasets generated by the ENCODE consortium. On average, lossless ChIPWig reduced the file sizes to merely 6% of the original, and offered 6-fold compression rate improvement compared to bigWig. The lossy feature further reduced file sizes 2-fold compared to the lossless mode, with little or no effects on peak calling and motif discovery using specialized NarrowPeaks methods. The compression and decompression speed rates are of the order of 0.2 sec/MB using general purpose computers. The source code and binaries are freely available for download at https://github.com/vidarmehr/ChIPWig-v2, implemented in C ++. milenkov@illinois.edu. Supplementary data are available at Bioinformatics online.

  5. 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.

  6. Wave Manipulation in Metamaterials: A LEGO® Bricks Enabled Platform

    Science.gov (United States)

    Celli, Paolo; Gonella, Stefano

    In this work, we show how simple, reconfigurable arrangements of LEGO® bricks can be turned into the building blocks of an experimental platform for the investigation of wave phenomena in metamaterial architectures. The approach involves the assembly of reconfigurable specimens consisting of patterns of bricks on a baseplate and the use of a 3D laser vibrometer to reconstruct global and local wave features. The ability to seamlessly transition between different topologies makes this an effective approach for rapid experimental verification and proof of concept in the arena of mechanical metamaterials engineering. The intuitive nature of the brick-and-baseplate assembly paradigm can also be leveraged to implement families of intuitive lab demonstrations with significant didactic and scientific outreach potential. The versatility of the platform is tested through a series of experiments that illustrate a variety of wave manipulation effects, such as waveguiding and seismic isolation, both in periodic and disordered topologies. We acknowledge the support of the National Science Foundation (Grant CMMI-1266089).

  7. Deep-Learning-Enabled On-Demand Design of Chiral Metamaterials.

    Science.gov (United States)

    Ma, Wei; Cheng, Feng; Liu, Yongmin

    2018-06-11

    Deep-learning framework has significantly impelled the development of modern machine learning technology by continuously pushing the limit of traditional recognition and processing of images, speech, and videos. In the meantime, it starts to penetrate other disciplines, such as biology, genetics, materials science, and physics. Here, we report a deep-learning-based model, comprising two bidirectional neural networks assembled by a partial stacking strategy, to automatically design and optimize three-dimensional chiral metamaterials with strong chiroptical responses at predesignated wavelengths. The model can help to discover the intricate, nonintuitive relationship between a metamaterial structure and its optical responses from a number of training examples, which circumvents the time-consuming, case-by-case numerical simulations in conventional metamaterial designs. This approach not only realizes the forward prediction of optical performance much more accurately and efficiently but also enables one to inversely retrieve designs from given requirements. Our results demonstrate that such a data-driven model can be applied as a very powerful tool in studying complicated light-matter interactions and accelerating the on-demand design of nanophotonic devices, systems, and architectures for real world applications.

  8. Terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-tong [Los Alamos National Laboratory; Taylor, Antoineete J [Los Alamos National Laboratory; Azad, Abul K [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory

    2009-01-01

    In this paper we present our recent developments in terahertz (THz) metamaterials and devices. Planar THz metamaterials and their complementary structures fabricated on suitable substrates have shown electric resonant response, which causes the band-pass or band-stop property in THz transmission and reflection. The operational frequency can be further tuned up to 20% upon photoexcitation of an integrated semiconductor region in the splitring resonators as the metamaterial elements. On the other hand, the use of semiconductors as metamaterial substrates enables dynamical control of metamaterial resonances through photoexcitation, and reducing the substrate carrier lifetime further enables an ultrafast switching recovery. The metamaterial resonances can also be actively controlled by application of a voltage bias when they are fabricated on semiconductor substrates with appropriate doping concentration and thickness. Using this electrically driven approach, THz modulation depth up to 80% and modulation speed of 2 MHz at room temperature have been demonstrated, which suggests practical THz applications.

  9. Photonic metamaterials

    International Nuclear Information System (INIS)

    Litchinitser, N M; Shalaev, V M

    2008-01-01

    The invention of metamaterials prompts reconsideration of a number of fundamental physical phenomena and enables a variety of unique properties and functionalities. These include negative refractive index, magnetism at optical frequencies, sub-wavelength resolution, ''backward'' phase matching conditions for nonlinear optical processes, and even rendering objects invisible – cloaking. In this brief review, recent progress in basic theory, design, fabrication, characterization, and potential applications of optical metamaterials is discussed

  10. Anomalous refraction of light colors by a metamaterial prism.

    Science.gov (United States)

    Silveirinha, Mário G

    2009-05-15

    A prism of glass separates white light into its spectral components in such a manner that colors associated with shorter wavelengths are more refracted than the colors associated with longer wavelengths. Here, we demonstrate that this property is not universal, and that a lossless metamaterial prism with a suitable microstructure may enable a broadband regime of anomalous dispersion, where the spectral components of light are separated in an unconventional way, so that "violet light" is less refracted than "red light." This phenomenon is fundamentally different from conventional anomalous dispersion effects, which are invariably accompanied by significant loss and are typically very narrow band.

  11. Photonic Band Structure of Dispersive Metamaterials Formulated as a Hermitian Eigenvalue Problem

    KAUST Repository

    Raman, Aaswath; Fan, Shanhui

    2010-01-01

    We formulate the photonic band structure calculation of any lossless dispersive photonic crystal and optical metamaterial as a Hermitian eigenvalue problem. We further show that the eigenmodes of such lossless systems provide an orthonormal basis, which can be used to rigorously describe the behavior of lossy dispersive systems in general. © 2010 The American Physical Society.

  12. Photonic Band Structure of Dispersive Metamaterials Formulated as a Hermitian Eigenvalue Problem

    KAUST Repository

    Raman, Aaswath

    2010-02-26

    We formulate the photonic band structure calculation of any lossless dispersive photonic crystal and optical metamaterial as a Hermitian eigenvalue problem. We further show that the eigenmodes of such lossless systems provide an orthonormal basis, which can be used to rigorously describe the behavior of lossy dispersive systems in general. © 2010 The American Physical Society.

  13. Lossless conditional schema evolution

    DEFF Research Database (Denmark)

    Jensen, Ole Guttorm; Böhlen, Michael

    2004-01-01

    is a precondition for a flexible semantics that allows to correctly answer general queries over evolving schemas. The key challenge is to handle attribute mismatches between the intended and recorded schema in a consistent way. We provide a parametric approach to resolve mismatches according to the needs......Conditional schema changes change the schema of the tuples that satisfy the change condition. When the schema of a relation changes some tuples may no longer fit the current schema. Handling the mismatch between the intended schema of tuples and the recorded schema of tuples is at the core...... of a DBMS that supports schema evolution. We propose to keep track of schema mismatches at the level of individual tuples, and prove that evolving schemas with conditional schema changes, in contrast to database systems relying on data migration, are lossless when the schema evolves. The lossless property...

  14. Novel frontier in quantum metamaterials (Conference Presentation)

    Science.gov (United States)

    Jha, Pankaj K.

    2016-09-01

    Metamaterials are artificial materials with exotic physical, chemical and optical properties not found in natural materials. In the past decade they have attracted monumental attention from the scientific community owing to their applications ranging from physics to engineering. However, the conventional solid-state metamaterial platforms suffer from inevitable optical loss, defects which severely curtain their application at few-photon level. The quest for quantum optical applications with metamaterial-based technologies has stimulated researchers to engineer novel lossless materials and construct new platforms. Recently, by integrating two important and timely realms of science - trapped atom physics and metamaterials -, we proposed and theoretically demonstrated a topologically reconfigurable and lossless quantum metamaterial. The atomic lattice quantum metamaterial is immune to aforementioned critical challenges and can be employed at a single-photon level. Moreover, in stark contrast to conventional solid-state platforms, optical lattices provide the necessary freedom to precisely localize (within few nanometer of uncertainty) a probe atom, inside the atomic lattice quantum metamaterial to harness its exotic optical properties. In addition to its aforementioned novel characteristics, our atomic lattice quantum metamaterial offers a unique degree of freedom, namely all-optical control on ultrafast time scales over the photonic topological transition of isofrequency contours using weak fields, not possible with previous solid-state platforms. In this work, we leverage the tools, techniques, scientific advances in the field of atomic, molecular and optical physics, integrated with the concepts used in metamaterials to propose and theoretically demonstrate a novel platform towards quantum metamaterial with novel functionalities by bringing together the best of two worlds.

  15. Micromachined tunable metamaterials: a review

    International Nuclear Information System (INIS)

    Liu, A Q; Zhu, W M; Tsai, D P; Zheludev, N I

    2012-01-01

    This paper reviews micromachined tunable metamaterials, whereby the tuning capabilities are based on the mechanical reconfiguration of the lattice and/or the metamaterial element geometry. The primary focus of this review is the feasibility of the realization of micromachined tunable metamaterials via structure reconfiguration and the current state of the art in the fabrication technologies of structurally reconfigurable metamaterial elements. The micromachined reconfigurable microstructures not only offer a new tuning method for metamaterials without being limited by the nonlinearity of constituent materials, but also enable a new paradigm of reconfigurable metamaterial-based devices with mechanical actuations. With recent development in nanomachining technology, it is possible to develop structurally reconfigurable metamaterials with faster tuning speed, higher density of integration and more flexible choice of the working frequencies. (review article)

  16. Lossless Conditional Schema Evolution

    DEFF Research Database (Denmark)

    Jensen, Ole Guttorm; Bøhlen, Michael Hanspeter

    2003-01-01

    The paper considers conditional schema evolution, where schema changes change the schema of the tuples that satisfy the change condition. When the schema of a relation change some tuples may no longer fit the current schema. Handling the mismatch between the intended schema of tuples and the reco......The paper considers conditional schema evolution, where schema changes change the schema of the tuples that satisfy the change condition. When the schema of a relation change some tuples may no longer fit the current schema. Handling the mismatch between the intended schema of tuples...... and the recorded schema of tuples is at the core of a DBMS that supports schema evolution. We propose to keep track of schema mismatches at the level of individual tuples, and prove that conditionally evolving schemas, in contrast to current commercial database systems, are lossless when the schema evolves...

  17. Lossless Compression of Broadcast Video

    DEFF Research Database (Denmark)

    Martins, Bo; Eriksen, N.; Faber, E.

    1998-01-01

    We investigate several techniques for lossless and near-lossless compression of broadcast video.The emphasis is placed on the emerging international standard for compression of continous-tone still images, JPEG-LS, due to its excellent compression performance and moderatecomplexity. Except for one...... cannot be expected to code losslessly at a rate of 125 Mbit/s. We investigate the rate and quality effects of quantization using standard JPEG-LS quantization and two new techniques: visual quantization and trellis quantization. Visual quantization is not part of baseline JPEG-LS, but is applicable...... in the framework of JPEG-LS. Visual tests show that this quantization technique gives much better quality than standard JPEG-LS quantization. Trellis quantization is a process by which the original image is altered in such a way as to make lossless JPEG-LS encoding more effective. For JPEG-LS and visual...

  18. Acoustic Metamaterials in Aeronautics

    Directory of Open Access Journals (Sweden)

    Giorgio Palma

    2018-06-01

    Full Text Available Metamaterials, man-made composites that are scaled smaller than the wavelength, have demonstrated a huge potential for application in acoustics, allowing the production of sub-wavelength acoustic absorbers, acoustic invisibility, perfect acoustic mirrors and acoustic lenses for hyper focusing, and acoustic illusions and enabling new degrees of freedom in the control of the acoustic field. The zero, or even negative, refractive sound index of metamaterials offers possibilities for the control of acoustic patterns and sound at sub-wavelength scales. Despite the tremendous growth in research on acoustic metamaterials during the last decade, the potential of metamaterial-based technologies in aeronautics has still not been fully explored, and its utilization is still in its infancy. Thus, the principal concepts mentioned above could very well provide a means to develop devices that allow the mitigation of the impact of civil aviation noise on the community. This paper gives a review of the most relevant works on acoustic metamaterials, analyzing them for their potential applicability in aeronautics, and, in this process, identifying possible implementation areas and interesting metabehaviors. It also identifies some technical challenges and possible future directions for research with the goal of unveiling the potential of metamaterials technology in aeronautics.

  19. Research Advance in Smart Metamaterials

    Directory of Open Access Journals (Sweden)

    YU Xiang-long

    2016-07-01

    Full Text Available Metamaterials, man-made materials, enable us to design our own "atoms", and thereby to create materials with unprecedented effective properties that have not yet been found in nature. Smart metamaterial is one of those that is an intelligent perceptive to the changes from external environments and simultaneously having the capability to respond to thermal and mechanical stimuli. This paper can provide a review on these smart metamaterials in perspective of science, engineering and industrial products. We divide smart metamaterials according to what they are tuning into: optical, mechanical, thermal and coupled smart metamaterials. The rest of two techniques we addressed are modelling/simulation and fabrication/gene engineering. All of these types smart materials presented here are associated with at least five fundamental research: coupled mechanism of multi-physics fields, man-made design for atom/molecular, metamaterials coupled with natural materials, tunability of metamaterials, and mechanism of sensing metamaterials. Therefore, we give a systematic overview of various potential smart metamaterials together with the upcoming challenges in the intriguing and promising research field.

  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. Metamaterial membranes

    International Nuclear Information System (INIS)

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2017-01-01

    We introduce a new class of metamaterial device to achieve separation of compounds by using coordinate transformations and metamaterial theory. By rationally designing the spatial anisotropy for mass diffusion, we simultaneously concentrate different compounds in different spatial locations, leading to separation of mixtures across a metamaterial membrane. The separation of mixtures into their constituent compounds is critically important in biophysics, biomedical, and chemical applications. We present a practical case where a mixture of oxygen and nitrogen diffusing through a polymeric planar matrix is separated. This work opens doors to new paradigms in membrane separations via coordinate transformations and metamaterials by introducing novel properties and unconventional mass diffusion phenomena. (paper)

  2. Spatial gradient tuning in metamaterials

    Science.gov (United States)

    Driscoll, Tom; Goldflam, Michael; Jokerst, Nan; Basov, Dimitri; Smith, David

    2011-03-01

    Gradient Index (GRIN) metamaterials have been used to create devices inspired by, but often surpassing the potential of, conventional GRIN optics. The unit-cell nature of metamaterials presents the opportunity to exert much greater control over spatial gradients than is possible in natural materials. This is true not only during the design phase but also offers the potential for real-time reconfiguration of the metamaterial gradient. This ability fits nicely into the picture of transformation-optics, in which spatial gradients can enable an impressive suite of innovative devices. We discuss methods to exert control over metamaterial response, focusing on our recent demonstrations using Vanadium Dioxide. We give special attention to role of memristance and mem-capacitance observed in Vanadium Dioxide, which simplify the demands of stimuli and addressing, as well as intersecting metamaterials with the field of memory-materials.

  3. 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...

  4. 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

  5. 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.

  6. Lossless, Near-Lossless, and Refinement Coding of Bi-level Images

    DEFF Research Database (Denmark)

    Martins, Bo; Forchhammer, Søren Otto

    1999-01-01

    We present general and unified algorithms for lossy/lossless coding of bi-level images. The compression is realized by applying arithmetic coding to conditional probabilities. As in the current JBIG standard the conditioning may be specified by a template.For better compression, the more general...... to the specialized soft pattern matching techniques which work better for text. Template based refinement coding is applied for lossy-to-lossless refinement. Introducing only a small amount of loss in halftoned test images, compression is increased by up to a factor of four compared with JBIG. Lossy, lossless......, and refinement decoding speed and lossless encoding speed are less than a factor of two slower than JBIG. The (de)coding method is proposed as part of JBIG2, an emerging international standard for lossless/lossy compression of bi-level images....

  7. Low-Complexity Lossless and Near-Lossless Data Compression Technique for Multispectral Imagery

    Science.gov (United States)

    Xie, Hua; Klimesh, Matthew A.

    2009-01-01

    This work extends the lossless data compression technique described in Fast Lossless Compression of Multispectral- Image Data, (NPO-42517) NASA Tech Briefs, Vol. 30, No. 8 (August 2006), page 26. The original technique was extended to include a near-lossless compression option, allowing substantially smaller compressed file sizes when a small amount of distortion can be tolerated. Near-lossless compression is obtained by including a quantization step prior to encoding of prediction residuals. The original technique uses lossless predictive compression and is designed for use on multispectral imagery. A lossless predictive data compression algorithm compresses a digitized signal one sample at a time as follows: First, a sample value is predicted from previously encoded samples. The difference between the actual sample value and the prediction is called the prediction residual. The prediction residual is encoded into the compressed file. The decompressor can form the same predicted sample and can decode the prediction residual from the compressed file, and so can reconstruct the original sample. A lossless predictive compression algorithm can generally be converted to a near-lossless compression algorithm by quantizing the prediction residuals prior to encoding them. In this case, since the reconstructed sample values will not be identical to the original sample values, the encoder must determine the values that will be reconstructed and use these values for predicting later sample values. The technique described here uses this method, starting with the original technique, to allow near-lossless compression. The extension to allow near-lossless compression adds the ability to achieve much more compression when small amounts of distortion are tolerable, while retaining the low complexity and good overall compression effectiveness of the original algorithm.

  8. Reversed rainbow with a nonlocal metamaterial

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Tiago A., E-mail: tiago.morgado@co.it.pt; Marcos, João S.; Silveirinha, Mário G., E-mail: mario.silveirinha@co.it.pt [Department of Electrical Engineering, Instituto de Telecomunicações, University of Coimbra, 3030 Coimbra (Portugal); Costa, João T. [CST AG, Bad Nauheimer Strasse 19, 64289 Darmstadt (Germany); Costa, Jorge R. [Instituto de Telecomunicações and Instituto Universitário de Lisboa (ISCTE-IUL), 1649-026 Lisboa (Portugal); Fernandes, Carlos A. [Instituto de Telecomunicações, and Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa (Portugal)

    2014-12-29

    One of the intriguing potentials of metamaterials is the possibility to realize a nonlocal electromagnetic reaction, such that the effective medium response at a given point is fundamentally entangled with the macroscopic field distribution at long distances. Here, it is experimentally and numerically verified that a microwave nonlocal metamaterial formed by crossed metallic wires enables a low-loss broadband anomalous material response such that the refractive index decreases with frequency. Notably, it is shown that an electromagnetic beam refracted by our metamaterial prism creates a reversed microwave rainbow.

  9. Toward high throughput optical metamaterial assemblies.

    Science.gov (United States)

    Fontana, Jake; Ratna, Banahalli R

    2015-11-01

    Optical metamaterials have unique engineered optical properties. These properties arise from the careful organization of plasmonic elements. Transitioning these properties from laboratory experiments to functional materials may lead to disruptive technologies for controlling light. A significant issue impeding the realization of optical metamaterial devices is the need for robust and efficient assembly strategies to govern the order of the nanometer-sized elements while enabling macroscopic throughput. This mini-review critically highlights recent approaches and challenges in creating these artificial materials. As the ability to assemble optical metamaterials improves, new unforeseen opportunities may arise for revolutionary optical devices.

  10. Lossless Compression of Video using Motion Compensation

    DEFF Research Database (Denmark)

    Martins, Bo; Forchhammer, Søren

    1998-01-01

    We investigate lossless coding of video using predictive coding andmotion compensation. The methods incorporate state-of-the-art lossless techniques such ascontext based prediction and bias cancellation, Golomb coding, high resolution motion field estimation,3d-dimensional predictors, prediction...... using one or multiple previous images, predictor dependent error modelling, and selection of motion field by code length. For slow pan or slow zoom sequences, coding methods that use multiple previous images are up to 20% better than motion compensation using a single previous image and up to 40% better...

  11. Lossless, Near-Lossless, and Refinement Coding of Bi-level Images

    DEFF Research Database (Denmark)

    Martins, Bo; Forchhammer, Søren Otto

    1997-01-01

    We present general and unified algorithms for lossy/lossless codingof bi-level images. The compression is realized by applying arithmetic coding to conditional probabilities. As in the current JBIG standard the conditioning may be specified by a template.For better compression, the more general....... Introducing only a small amount of loss in halftoned test images, compression is increased by up to a factor of four compared with JBIG. Lossy, lossless, and refinement decoding speed and lossless encoding speed are less than a factor of two slower than JBIG. The (de)coding method is proposed as part of JBIG......-2, an emerging international standard for lossless/lossy compression of bi-level images....

  12. Design of Metamaterials for control of electromagnetic waves

    Science.gov (United States)

    Koschny, Thomas

    2014-03-01

    Metamaterials are artificial effective media supporting propagating waves that derive their properties form the average response of deliberately designed and arranged, usually resonant scatterers with structural length-scales much smaller than the wavelength inside the material. Electromagnetic metamaterials are the most important implementation of metamaterials, which are made from deeply sub-wavelength electric, magnetic and chiral resonators and can be designed to work from radio frequencies all the way to visible light. Metamaterials have been major new development in physics and materials science over the last decade and are still attracting more interest as they enable us to create materials with unique properties like negative refraction, flat and super lenses, impedance matching eliminating reflection, perfect absorbers, deeply sub-wavelength sized wave guides and cavities, tunability, enhanced non-linearity and gain, chirality and huge optical activity, control of Casimir forces, and spontaneous emission, etc. In this talk, I will discuss the design, numerical simulation, and mathematical modeling of metamaterials. I will survey the current state of the art and discuss challenges, possible solutions and perspectives. In particular, the problem of dissipative loss and their possible compensation by incorporating spatially distributed gain in metamaterials. If the gain sub-system is strongly coupled to the sub-wavelength resonators of the metamaterial loss compensation and undamping of the resonant response of the metamaterials can occur. I will explore new, alternative dielectric low loss resonators for metamaterials as well as the potential of new conducting materials such as Graphene to replace metals as the conducting material in resonant metamaterials. Two dimensional metamaterials or metasurfaces, implementations of effective electromagnetic current sheets in which both electric and magnetic sheet conductivities are controlled by the average response

  13. Lossless Coding Standards for Space Data Systems

    Science.gov (United States)

    Rice, R. F.

    1996-01-01

    The International Consultative Committee for Space Data Systems (CCSDS) is preparing to issue its first recommendation for a digital data compression standard. Because the space data systems of primary interest are employed to support scientific investigations requiring accurate representation, this initial standard will be restricted to lossless compression.

  14. Metamaterial antennas: the most successful metamaterial technology?

    DEFF Research Database (Denmark)

    Breinbjerg, Olav

    2015-01-01

    The Thomson Reuters Web of Science™ lists more than 1500 journal articles related to metamaterial antennas from 2001 to 2015; this paper overviews some major objectives of such antennas.......The Thomson Reuters Web of Science™ lists more than 1500 journal articles related to metamaterial antennas from 2001 to 2015; this paper overviews some major objectives of such antennas....

  15. Unified approach for retrieval of effective parameters of metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, Sangwoo; Sukhorukov, Andrey A.

    2011-01-01

    that our method is able to retrieve both material and wave EPs for a wide range of materials, which can be lossy or lossless, dispersive, possess negative permittivity, permeability and refractive index values. It is simple and unambiguous, free of the "branch" problem, which is an issue for the reflection....../transmission based method and has no limitations on a metamaterial slab thickness. The method does not require averaging different fields' components at various surfaces or contours. The retrieval of both wave and material EPs is performed within a single computational cycle, after exporting fields on the unit cells...

  16. Optical programmable metamaterials

    Science.gov (United States)

    Gong, Cheng; Zhang, Nan; Dai, Zijie; Liu, Weiwei

    2018-02-01

    We suggest and demonstrate the concept of optical programmable metamaterials which can configure the device's electromagnetic parameters by the programmable optical stimuli. In such metamaterials, the optical stimuli produced by a FPGA controlled light emitting diode array can switch or combine the resonance modes which are coupled in. As an example, an optical programmable metamaterial terahertz absorber is proposed. Each cell of the absorber integrates four meta-rings (asymmetric 1/4 rings) with photo-resistors connecting the critical gaps. The principle and design of the metamaterials are illustrated and the simulation results demonstrate the functionalities for programming the metamaterial absorber to change its bandwidth and resonance frequency.

  17. Active terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-tong [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory

    2009-01-01

    In this paper we present an overview of research in our group in terahertz (THz) metamaterials and their applications. We have developed a series of planar metamaterials operating at THz frequencies, all of which exhibit a strong resonant response. By incorporating natural materials, e.g. semiconductors, as the substrates or as critical regions of metamaterial elements, we are able to effectively control the metamaterial resonance by the application of external stimuli, e.g., photoexcitation and electrical bias. Such actively controllable metamaterials provide novel functionalities for solid-state device applications with unprecedented performance, such as THz spectroscopy, imaging, and many others.

  18. Metamaterials beyond electromagnetism

    International Nuclear Information System (INIS)

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

    2013-01-01

    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. (review article)

  19. 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.

  20. Survey Of Lossless Image Coding Techniques

    Science.gov (United States)

    Melnychuck, Paul W.; Rabbani, Majid

    1989-04-01

    Many image transmission/storage applications requiring some form of data compression additionally require that the decoded image be an exact replica of the original. Lossless image coding algorithms meet this requirement by generating a decoded image that is numerically identical to the original. Several lossless coding techniques are modifications of well-known lossy schemes, whereas others are new. Traditional Markov-based models and newer arithmetic coding techniques are applied to predictive coding, bit plane processing, and lossy plus residual coding. Generally speaking, the compression ratio offered by these techniques are in the area of 1.6:1 to 3:1 for 8-bit pictorial images. Compression ratios for 12-bit radiological images approach 3:1, as these images have less detailed structure, and hence, their higher pel correlation leads to a greater removal of image redundancy.

  1. A Lossless Network for Data Acquisition

    OpenAIRE

    Jereczek, Grzegorz Edmund; Lehmann Miotto, Giovanna

    2016-01-01

    The bursty many-to-one communication pattern, typical for data acquisition systems, is particularly demanding for commodity TCP/IP and Ethernet technologies. We expand the study of lossless switching in software running on commercial-off-the-shelf servers, using the ATLAS experiment as a case study. In this paper we extend the popular software switch, Open vSwitch, with a dedicated, throughput-oriented buffering mechanism for data acquisition. We compare the performance under heavy congestion...

  2. Lossless compression for 3D PET

    International Nuclear Information System (INIS)

    Macq, B.; Sibomana, M.; Coppens, A.; Bol, A.; Michel, C.

    1994-01-01

    A new adaptive scheme is proposed for the lossless compression of positron emission tomography (PET) sinogram data. The algorithm uses an adaptive differential pulse code modulator (ADPCM) followed by a universal variable length coder (UVLC). Contrasting with Lempel-Ziv (LZ), which operates on a whole sinogram, UVLC operates very efficiently on short data blocks. This is a major advantage for real-time implementation. The algorithm is adaptive and codes data after some on-line estimations of the statistics inside each block. Its efficiency is tested when coding dynamic and static scans from two PET scanners and reaches asymptotically the entropy limit for long frames. For very short 3D frames, the new algorithm is twice more efficient than LZ. Since an ASIC implementing a similar UVLC scheme is available today, a similar one should be able to sustain PET data lossless compression and decompression at a rate of 27 MBytes/sec. This algorithm is consequently a good candidate for the next generation of lossless compression engine

  3. Lossless compression for 3D PET

    International Nuclear Information System (INIS)

    Macq, B.; Sibomana, M.; Coppens, A.; Bol, A.; Michel, C.; Baker, K.; Jones, B.

    1994-01-01

    A new adaptive scheme is proposed for the lossless compression of positron emission tomography (PET) sinogram data. The algorithm uses an adaptive differential pulse code modulator (ADPCM) followed by a universal variable length coder (UVLC). Contrasting with Lempel-Ziv (LZ), which operates on a whole sinogram, UVLC operates very efficiently on short data blocks. This is a major advantage for real-time implementation. The algorithms is adaptive and codes data after some on-line estimations of the statistics inside each block. Its efficiency is tested when coding dynamic and static scans from two PET scanners and reaches asymptotically the entropy limit for long frames. For very short 3D frames, the new algorithm is twice more efficient than LZ. Since an application specific integrated circuit (ASIC) implementing a similar UVLC scheme is available today, a similar one should be able to sustain PET data lossless compression and decompression at a rate of 27 MBytes/sec. This algorithm is consequently a good candidate for the next generation of lossless compression engine

  4. Scalable-to-lossless transform domain distributed video coding

    DEFF Research Database (Denmark)

    Huang, Xin; Ukhanova, Ann; Veselov, Anton

    2010-01-01

    Distributed video coding (DVC) is a novel approach providing new features as low complexity encoding by mainly exploiting the source statistics at the decoder based on the availability of decoder side information. In this paper, scalable-tolossless DVC is presented based on extending a lossy Tran...... codec provides frame by frame encoding. Comparing the lossless coding efficiency, the proposed scalable-to-lossless TDWZ video codec can save up to 5%-13% bits compared to JPEG LS and H.264 Intra frame lossless coding and do so as a scalable-to-lossless coding....

  5. 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....

  6. Faraday wave lattice as an elastic metamaterial.

    Science.gov (United States)

    Domino, L; Tarpin, M; Patinet, S; Eddi, A

    2016-05-01

    Metamaterials enable the emergence of novel physical properties due to the existence of an underlying subwavelength structure. Here, we use the Faraday instability to shape the fluid-air interface with a regular pattern. This pattern undergoes an oscillating secondary instability and exhibits spontaneous vibrations that are analogous to transverse elastic waves. By locally forcing these waves, we fully characterize their dispersion relation and show that a Faraday pattern presents an effective shear elasticity. We propose a physical mechanism combining surface tension with the Faraday structured interface that quantitatively predicts the elastic wave phase speed, revealing that the liquid interface behaves as an elastic metamaterial.

  7. 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 functionalities...

  8. Multiband and Lossless Compression of Hyperspectral Images

    Directory of Open Access Journals (Sweden)

    Raffaele Pizzolante

    2016-02-01

    Full Text Available Hyperspectral images are widely used in several real-life applications. In this paper, we investigate on the compression of hyperspectral images by considering different aspects, including the optimization of the computational complexity in order to allow implementations on limited hardware (i.e., hyperspectral sensors, etc.. We present an approach that relies on a three-dimensional predictive structure. Our predictive structure, 3D-MBLP, uses one or more previous bands as references to exploit the redundancies among the third dimension. The achieved results are comparable, and often better, with respect to the other state-of-art lossless compression techniques for hyperspectral images.

  9. Metamaterials and plasmonics: From nanoparticles to nanoantenna arrays, metasurfaces, and metamaterials

    International Nuclear Information System (INIS)

    Monticone Francesco; Alù Andrea

    2014-01-01

    The rise of plasmonic metamaterials in recent years has unveiled the possibility of revolutionizing the entire field of optics and photonics, challenging well-established technological limitations and paving the way to innovations at an unprecedented level. To capitalize the disruptive potential of this rising field of science and technology, it is important to be able to combine the richness of optical phenomena enabled by nanoplasmonics in order to realize metamaterial components, devices, and systems of increasing complexity. Here, we review a few recent research directions in the field of plasmonic metamaterials, which may foster further advancements in this research area. We will discuss the anomalous scattering features enabled by plasmonic nanoparticles and nanoclusters, and show how they may represent the fundamental building blocks of complex nanophotonic architectures. Building on these concepts, advanced components can be designed and operated, such as optical nanoantennas and nanoantenna arrays, which, in turn, may be at the basis of metasurface devices and complex systems. Following this path, from basic phenomena to advanced functionalities, the field of plasmonic metamaterials offers the promise of an important scientific and technological impact, with applications spanning from medical diagnostics to clean energy and information processing. (topical review - plasmonics and metamaterials)

  10. 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

  11. 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

  12. A Lossless Network for Data Acquisition

    Science.gov (United States)

    Jereczek, Grzegorz; Lehmann Miotto, Giovanna; Malone, David; Walukiewicz, Miroslaw

    2017-06-01

    The bursty many-to-one communication pattern, typical for data acquisition systems, is particularly demanding for commodity TCP/IP and Ethernet technologies. We expand the study of lossless switching in software running on commercial off-the-shelf servers, using the ATLAS experiment as a case study. In this paper, we extend the popular software switch, Open vSwitch, with a dedicated, throughput-oriented buffering mechanism for data acquisition. We compare the performance under heavy congestion on typical Ethernet switches to a commodity server acting as a switch. Our results indicate that software switches with large buffers perform significantly better. Next, we evaluate the scalability of the system when building a larger topology of interconnected software switches, exploiting the integration with software-defined networking technologies. We build an IP-only leaf-spine network consisting of eight software switches running on distinct physical servers as a demonstrator.

  13. A Lossless Network for Data Acquisition

    CERN Document Server

    AUTHOR|(SzGeCERN)698154; The ATLAS collaboration; Lehmann Miotto, Giovanna

    2016-01-01

    The planned upgrades of the experiments at the Large Hadron Collider at CERN will require higher bandwidth networks for their data acquisition systems. The network congestion problem arising from the bursty many-to-one communication pattern, typical for these systems, will become more demanding. It is questionable whether commodity TCP/IP and Ethernet technologies in their current form will be still able to effectively adapt to the bursty traffic without losing packets due to the scarcity of buffers in the networking hardware. We continue our study of the idea of lossless switching in software running on commercial-off-the-shelf servers for data acquisition systems, using the ATLAS experiment as a case study. The flexibility of design in software, performance of modern computer platforms, and buffering capabilities constrained solely by the amount of DRAM memory are a strong basis for building a network dedicated to data acquisition with commodity hardware, which can provide reliable transport in congested co...

  14. A Lossless Network for Data Acquisition

    CERN Document Server

    AUTHOR|(SzGeCERN)698154; The ATLAS collaboration; Lehmann Miotto, Giovanna

    2017-01-01

    The bursty many-to-one communication pattern, typical for data acquisition systems, is particularly demanding for commodity TCP/IP and Ethernet technologies. We expand the study of lossless switching in software running on commercial-off-the-shelf servers, using the ATLAS experiment as a case study. In this paper we extend the popular software switch, Open vSwitch, with a dedicated, throughput-oriented buffering mechanism for data acquisition. We compare the performance under heavy congestion on typical Ethernet switches to a commodity server acting as a switch. Our results indicate that software switches with large buffers perform significantly better. Next, we evaluate the scalability of the system when building a larger topology of interconnected software switches, exploiting the integration with software-defined networking technologies. We build an IP-only leaf-spine network consisting of eight software switches running on separate physical servers as a demonstrator.

  15. A Lossless Switch for Data Acquisition Networks

    CERN Document Server

    Jereczek, Grzegorz Edmund; The ATLAS collaboration

    2015-01-01

    The recent trends in software-defined networking (SDN) and network function virtualization (NFV) are boosting the advance of software-based packet processing and forwarding on commodity servers. Although performance has traditionally been the challenge of this approach, this situation changes with modern server platforms. High performance load balancers, proxies, virtual switches and other network functions can be now implemented in software and not limited to specialized commercial hardware, thus reducing cost and increasing the flexibility. In this paper we design a lossless software-based switch for high bandwidth data acquisition (DAQ) networks, using the ATLAS experiment at CERN as a case study. We prove that it can effectively solve the incast pathology arising from the many-to-one communication pattern present in DAQ networks by providing extremely high buffering capabilities. We evaluate this on a commodity server equipped with twelve 10 Gbps Ethernet interfaces providing a total bandwidth of 120 Gbps...

  16. 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.

  17. The role of lossless systems in modern digital signal processing: a tutorial

    OpenAIRE

    Vaidyanathan, P. P.; Doğanata, Zinnur

    1989-01-01

    A self-contained discussion of discrete-time lossless systems and their properties and relevance in digital signal processing is presented. The basic concept of losslessness is introduced, and several algebraic properties of lossless systems are studied. An understanding of these properties is crucial in order to exploit the rich usefulness of lossless systems in digital signal processing. Since lossless systems typically have many input and output terminals, a brief review of multiinput mult...

  18. 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

  19. 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

  20. Theory and design of nonlinear metamaterials

    Science.gov (United States)

    Rose, Alec Daniel

    If electronics are ever to be completely replaced by optics, a significant possibility in the wake of the fiber revolution, it is likely that nonlinear materials will play a central and enabling role. Indeed, nonlinear optics is the study of the mechanisms through which light can change the nature and properties of matter and, as a corollary, how one beam or color of light can manipulate another or even itself within such a material. However, of the many barriers preventing such a lofty goal, the narrow and limited range of properties supported by nonlinear materials, and natural materials in general, stands at the forefront. Many industries have turned instead to artificial and composite materials, with homogenizable metamaterials representing a recent extension of such composites into the electromagnetic domain. In particular, the inclusion of nonlinear elements has caused metamaterials research to spill over into the field of nonlinear optics. Through careful design of their constituent elements, nonlinear metamaterials are capable of supporting an unprecedented range of interactions, promising nonlinear devices of novel design and scale. In this context, I cast the basic properties of nonlinear metamaterials in the conventional formalism of nonlinear optics. Using alternately transfer matrices and coupled mode theory, I develop two complementary methods for characterizing and designing metamaterials with arbitrary nonlinear properties. Subsequently, I apply these methods in numerical studies of several canonical metamaterials, demonstrating enhanced electric and magnetic nonlinearities, as well as predicting the existence of nonlinear magnetoelectric and off-diagonal nonlinear tensors. I then introduce simultaneous design of the linear and nonlinear properties in the context of phase matching, outlining five different metamaterial phase matching methods, with special emphasis on the phase matching of counter propagating waves in mirrorless parametric amplifiers

  1. Two-dimensional metamaterial optics

    International Nuclear Information System (INIS)

    Smolyaninov, I I

    2010-01-01

    While three-dimensional photonic metamaterials are difficult to fabricate, many new concepts and ideas in the metamaterial optics can be realized in two spatial dimensions using planar optics of surface plasmon polaritons. In this paper we review recent progress in this direction. Two-dimensional photonic crystals, hyperbolic metamaterials, and plasmonic focusing devices are demonstrated and used in novel microscopy and waveguiding schemes

  2. Active control of a plasmonic metamaterial for quantum state engineering

    Science.gov (United States)

    Uriri, S. A.; Tashima, T.; Zhang, X.; Asano, M.; Bechu, M.; Güney, D. Ö.; Yamamoto, T.; Özdemir, Ş. K.; Wegener, M.; Tame, M. S.

    2018-05-01

    We experimentally demonstrate the active control of a plasmonic metamaterial operating in the quantum regime. A two-dimensional metamaterial consisting of unit cells made from gold nanorods is investigated. Using an external laser, we control the temperature of the metamaterial and carry out quantum process tomography on single-photon polarization-encoded qubits sent through, characterizing the metamaterial as a variable quantum channel. The overall polarization response can be tuned by up to 33% for particular nanorod dimensions. To explain the results, we develop a theoretical model and find that the experimental results match the predicted behavior well. This work goes beyond the use of simple passive quantum plasmonic systems and shows that external control of plasmonic elements enables a flexible device that can be used for quantum state engineering.

  3. 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.

  4. Effects of Metamaterial Slabs Applied to Wireless Power Transfer at 13.56 MHz

    OpenAIRE

    Kim, Gunyoung; Oh, Taek-Kyu; Lee, Bomson

    2015-01-01

    This paper analyzes the effects of a metamaterial slab (or a practical “perfect lens”) with negative permeability applied to a two loop magnetically coupled wireless power transfer (WPT) system at 13.56 MHz, based on theory, full-wave electromagnetic- (EM-) simulations, and measurements. When using lossless slabs with ideal negative permeability in EM-simulations, the WPT efficiencies have been found to be enhanced close to 100% due to the magnetic field focusing. For the case of using a real...

  5. Comparison of spatial harmonics in infinite and finite Bragg stacks for metamaterial homogenization

    DEFF Research Database (Denmark)

    Clausen, Niels Christian Jerichau; Arslanagic, Samel; Breinbjerg, Olav

    2014-01-01

    Metamaterial homogenization may be based on the dominance of a single Floquet-Bloch spatial harmonic in an infinite periodic structure - with the dominance quantified in terms of the relative magnitude of the associated spatial harmonic Poynting vector. For the corresponding finite structure...... the field is not quasi-periodic and cannot be expanded in Floquet-Bloch spatial harmonics; however, a set of pseudo spatial harmonics can be defined and the dominance of a single such harmonic likewise be used to determine whether the structure can be homogenized. For three different lossless Bragg stack...

  6. Lossless Compression of Classification-Map Data

    Science.gov (United States)

    Hua, Xie; Klimesh, Matthew

    2009-01-01

    A lossless image-data-compression algorithm intended specifically for application to classification-map data is based on prediction, context modeling, and entropy coding. The algorithm was formulated, in consideration of the differences between classification maps and ordinary images of natural scenes, so as to be capable of compressing classification- map data more effectively than do general-purpose image-data-compression algorithms. Classification maps are typically generated from remote-sensing images acquired by instruments aboard aircraft (see figure) and spacecraft. A classification map is a synthetic image that summarizes information derived from one or more original remote-sensing image(s) of a scene. The value assigned to each pixel in such a map is the index of a class that represents some type of content deduced from the original image data for example, a type of vegetation, a mineral, or a body of water at the corresponding location in the scene. When classification maps are generated onboard the aircraft or spacecraft, it is desirable to compress the classification-map data in order to reduce the volume of data that must be transmitted to a ground station.

  7. 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.

  8. New Physics of Metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhong-Yue, E-mail: zhongyuewang@ymail.com

    2014-06-15

    Einstein utilized Lorentz invariance from Maxwell's equations to modify mechanical laws and establish the special theory of relativity. Similarly, we may have a different theory if there exists another covariance of Maxwell's equations. In this paper, we find such a new transformation where Maxwell's equations are still unchanged. Consequently, Veselago's metamaterial and other systems have negative phase velocities without double negative permittivity and permeability can be described by a unified theory. People are interested in the application of metamaterials and negative phase velocities but do not appreciate the magnitude and significance to the spacetime conception of modern physics and philosophy.

  9. Fast lossless compression via cascading Bloom filters.

    Science.gov (United States)

    Rozov, Roye; Shamir, Ron; Halperin, Eran

    2014-01-01

    Data from large Next Generation Sequencing (NGS) experiments present challenges both in terms of costs associated with storage and in time required for file transfer. It is sometimes possible to store only a summary relevant to particular applications, but generally it is desirable to keep all information needed to revisit experimental results in the future. Thus, the need for efficient lossless compression methods for NGS reads arises. It has been shown that NGS-specific compression schemes can improve results over generic compression methods, such as the Lempel-Ziv algorithm, Burrows-Wheeler transform, or Arithmetic Coding. When a reference genome is available, effective compression can be achieved by first aligning the reads to the reference genome, and then encoding each read using the alignment position combined with the differences in the read relative to the reference. These reference-based methods have been shown to compress better than reference-free schemes, but the alignment step they require demands several hours of CPU time on a typical dataset, whereas reference-free methods can usually compress in minutes. We present a new approach that achieves highly efficient compression by using a reference genome, but completely circumvents the need for alignment, affording a great reduction in the time needed to compress. In contrast to reference-based methods that first align reads to the genome, we hash all reads into Bloom filters to encode, and decode by querying the same Bloom filters using read-length subsequences of the reference genome. Further compression is achieved by using a cascade of such filters. Our method, called BARCODE, runs an order of magnitude faster than reference-based methods, while compressing an order of magnitude better than reference-free methods, over a broad range of sequencing coverage. In high coverage (50-100 fold), compared to the best tested compressors, BARCODE saves 80-90% of the running time while only increasing space

  10. Unravelling Origami Metamaterial Behavior

    Science.gov (United States)

    Eidini, Maryam; Paulino, Glaucio

    2015-03-01

    Origami has shown to be a substantial source of inspiration for innovative design of mechanical metamaterials for which the material properties arise from their geometry and structural layout. Most research on origami-inspired materials relies on known patterns, especially on classic Miura-ori pattern. In the present research, we have created origami-inspired metamaterials and we have shown that the folded materials possess properties as remarkable as those of Miura-ori on which there is a lot of recent research. We have also introduced and placed emphasis on several important concepts that are confused or overlooked in the literature, e.g. concept of planar Poisson's ratio for folded materials from different conceptual viewpoints, and we have clarified the importance of such concepts by applying them to the folded sheet metamaterials introduced in our research. The new patterns are appropriate for a broad range of applications, from mechanical metamaterials to deployable and kinetic structures, at both small and large scales.

  11. Active Microwave Metamaterials Incorporating Ideal Gain Devices

    Directory of Open Access Journals (Sweden)

    Hao Xin

    2010-12-01

    Full Text Available Incorporation of active devices/media such as transistors for microwave and gain media for optics may be very attractive for enabling desired low loss and broadband metamaterials. Such metamaterials can even have gain which may very well lead to new and exciting physical phenomena. We investigate microwave composite right/left-handed transmission lines (CRLH-TL incorporating ideal gain devices such as constant negative resistance. With realistic lumped element values, we have shown that the negative phase constant of this kind of transmission lines is maintained (i.e., left-handedness kept while gain can be obtained (negative attenuation constant of transmission line simultaneously. Possible implementation and challenging issues of the proposed active CRLH-TL are also discussed.

  12. Lossless quantum data compression and variable-length coding

    International Nuclear Information System (INIS)

    Bostroem, Kim; Felbinger, Timo

    2002-01-01

    In order to compress quantum messages without loss of information it is necessary to allow the length of the encoded messages to vary. We develop a general framework for variable-length quantum messages in close analogy to the classical case and show that lossless compression is only possible if the message to be compressed is known to the sender. The lossless compression of an ensemble of messages is bounded from below by its von-Neumann entropy. We show that it is possible to reduce the number of qbits passing through a quantum channel even below the von Neumann entropy by adding a classical side channel. We give an explicit communication protocol that realizes lossless and instantaneous quantum data compression and apply it to a simple example. This protocol can be used for both online quantum communication and storage of quantum data

  13. Electrically driven hybrid photonic metamaterials for multifunctional control

    Science.gov (United States)

    Kang, Lei; Liu, Liu; Campbell, Sawyer D.; Yue, Taiwei; Ren, Qiang; Mayer, Theresa S.; Werner, Douglas H.

    2017-08-01

    The unique light-matter interaction in metamaterials, a type of artificial medium in which the geometrical features of subunits dominate their optical responses, have been utilized to achieve exotic material properties that are rare or nonexistent in natural materials. Furthermore, to extend their behaviors, active materials have been introduced into metamaterial systems to advance tunability, switchability and nonlinearity. Nevertheless, practical examples of versatile photonic metamaterials remain exceedingly rare for two main reasons. On the one hand, in sharp contrast to the broad material options available at lower frequencies, it is less common to find active media in the optical regime that can provide pronounced dielectric property changes under external stimuli, such as electric and magnetic fields. Vanadium dioxide (VO2), offering a large refractive index variation over a broad frequency range due to its near room temperature insulator-to-metal transition (IMT), has been favored in recent studies on tunable metamaterials. On the other hand, it turns out that regulating responses of hybrid metamaterials to external forces in an integrated manner is not a straightforward task. Recently, metamaterial-enabled devices (i.e., metadevices) with `self-sufficient' or `self-contained' electrical and optical properties have enabled complex functionalities. Here, we present a design methodology along with the associated experimental validation of a VO2 thin film integrated optical metamaterial absorber as a hybrid photonic platform for electrically driven multifunctional control, including reflectance switching, a rewritable memory process and manageable localized camouflage. The nanoengineered topologically continuous metal structure simultaneously supports the optical resonance and electrical functionality that actuates the phase transition in VO2 through the process of Joule heating. This work provides a universal approach to creating self-sufficient and highly

  14. 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.

  15. A review of lossless audio compression standards and algorithms

    Science.gov (United States)

    Muin, Fathiah Abdul; Gunawan, Teddy Surya; Kartiwi, Mira; Elsheikh, Elsheikh M. A.

    2017-09-01

    Over the years, lossless audio compression has gained popularity as researchers and businesses has become more aware of the need for better quality and higher storage demand. This paper will analyse various lossless audio coding algorithm and standards that are used and available in the market focusing on Linear Predictive Coding (LPC) specifically due to its popularity and robustness in audio compression, nevertheless other prediction methods are compared to verify this. Advanced representation of LPC such as LSP decomposition techniques are also discussed within this paper.

  16. 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.

  17. Homogenization of resonant chiral metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Menzel, C.; Rockstuhl, Carsten

    2010-01-01

    Homogenization of metamaterials is a crucial issue as it allows to describe their optical response in terms of effective wave parameters as, e.g., propagation constants. In this paper we consider the possible homogenization of chiral metamaterials. We show that for meta-atoms of a certain size...... an analytical criterion for performing the homogenization and a tool to predict the homogenization limit. We show that strong coupling between meta-atoms of chiral metamaterials may prevent their homogenization at all....

  18. 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...

  19. 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.

  20. Technical note: New table look-up lossless compression method ...

    African Journals Online (AJOL)

    Technical note: New table look-up lossless compression method based on binary index archiving. ... International Journal of Engineering, Science and Technology ... This paper intends to present a common use archiver, made up following the dictionary technique and using the index archiving method as a simple and ...

  1. Improved lossless intra coding for H.264/MPEG-4 AVC.

    Science.gov (United States)

    Lee, Yung-Lyul; Han, Ki-Hun; Sullivan, Gary J

    2006-09-01

    A new lossless intra coding method based on sample-by-sample differential pulse code modulation (DPCM) is presented as an enhancement of the H.264/MPEG-4 AVC standard. The H.264/AVC design includes a multidirectional spatial prediction method to reduce spatial redundancy by using neighboring samples as a prediction for the samples in a block of data to be encoded. In the new lossless intra coding method, the spatial prediction is performed based on samplewise DPCM instead of in the block-based manner used in the current H.264/AVC standard, while the block structure is retained for the residual difference entropy coding process. We show that the new method, based on samplewise DPCM, does not have a major complexity penalty, despite its apparent pipeline dependencies. Experiments show that the new lossless intra coding method reduces the bit rate by approximately 12% in comparison with the lossless intra coding method previously included in the H.264/AVC standard. As a result, the new method is currently being adopted into the H.264/AVC standard in a new enhancement project.

  2. GPU Lossless Hyperspectral Data Compression System for Space Applications

    Science.gov (United States)

    Keymeulen, Didier; Aranki, Nazeeh; Hopson, Ben; Kiely, Aaron; Klimesh, Matthew; Benkrid, Khaled

    2012-01-01

    On-board lossless hyperspectral data compression reduces data volume in order to meet NASA and DoD limited downlink capabilities. At JPL, a novel, adaptive and predictive technique for lossless compression of hyperspectral data, named the Fast Lossless (FL) algorithm, was recently developed. This technique uses an adaptive filtering method and achieves state-of-the-art performance in both compression effectiveness and low complexity. Because of its outstanding performance and suitability for real-time onboard hardware implementation, the FL compressor is being formalized as the emerging CCSDS Standard for Lossless Multispectral & Hyperspectral image compression. The FL compressor is well-suited for parallel hardware implementation. A GPU hardware implementation was developed for FL targeting the current state-of-the-art GPUs from NVIDIA(Trademark). The GPU implementation on a NVIDIA(Trademark) GeForce(Trademark) GTX 580 achieves a throughput performance of 583.08 Mbits/sec (44.85 MSamples/sec) and an acceleration of at least 6 times a software implementation running on a 3.47 GHz single core Intel(Trademark) Xeon(Trademark) processor. This paper describes the design and implementation of the FL algorithm on the GPU. The massively parallel implementation will provide in the future a fast and practical real-time solution for airborne and space applications.

  3. Lossless Compression of Stereo Disparity Maps for 3D

    DEFF Research Database (Denmark)

    Zamarin, Marco; Forchhammer, Søren

    2012-01-01

    Efficient compression of disparity data is important for accurate view synthesis purposes in multi-view communication systems based on the “texture plus depth” format, including the stereo case. In this paper a novel technique for lossless compression of stereo disparity images is presented...

  4. Perforated membrane-type acoustic metamaterials

    International Nuclear Information System (INIS)

    Langfeldt, F.; Kemsies, H.; Gleine, W.; Estorff, O. von

    2017-01-01

    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.

  5. 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.

  6. Hierarchical honeycomb auxetic metamaterials

    Science.gov (United States)

    Mousanezhad, Davood; Babaee, Sahab; Ebrahimi, Hamid; Ghosh, Ranajay; Hamouda, Abdelmagid Salem; Bertoldi, Katia; Vaziri, Ashkan

    2015-12-01

    Most conventional materials expand in transverse directions when they are compressed uniaxially resulting in the familiar positive Poisson’s ratio. Here we develop a new class of two dimensional (2D) metamaterials with negative Poisson’s ratio that contract in transverse directions under uniaxial compressive loads leading to auxeticity. This is achieved through mechanical instabilities (i.e., buckling) introduced by structural hierarchy and retained over a wide range of applied compression. This unusual behavior is demonstrated experimentally and analyzed computationally. The work provides new insights into the role of structural organization and hierarchy in designing 2D auxetic metamaterials, and new opportunities for developing energy absorbing materials, tunable membrane filters, and acoustic dampeners.

  7. Design, Analysis, and Characterization of Metamaterial Quasi-Optical Components for Millimeter-Wave Automotive Radar

    Science.gov (United States)

    Nguyen, Vinh Ngoc

    Since their introduction by Mercedes Benz in the late 1990s, W-band radars operating at 76-77 GHz have found their way into more and more passenger cars. These automotive radars are typically used in adaptive cruise control, pre-collision sensing, and other driver assistance systems. While these systems are usually only about the size of two stacked cigarette packs, system size, and weight remains a concern for many automotive manufacturers. In this dissertation, I discuss how artificially structured metamaterials can be used to improve lens-based automotive radar systems. Metamaterials allow the fabrication of smaller and lighter systems, while still meeting the frequency, high gain, and cost requirements of this application. In particular, I focus on the development of planar artificial dielectric lenses suitable for use in place of the injection-molded lenses now used in many automotive radar systems. I begin by using analytic and numerical ray-tracing to compare the performance of planar metamaterial GRIN lenses to equivalent aspheric refractive lenses. I do this to determine whether metamaterials are best employed in GRIN or refractive automotive radar lenses. Through this study I find that planar GRIN lenses with the large refractive index ranges enabled by metamaterials have approximately optically equivalent performance to equivalent refractive lenses for fields of view approaching +/-20°. I also find that the uniaxial nature of most planar metamaterials does not negatively impact planar GRIN lens performance. I then turn my attention to implementing these planar GRIN lenses at W-band automotive radar frequencies. I begin by designing uniform sheets of W-band electrically-coupled LC resonator-based metamaterials. These metamaterial samples were fabricated by the Jokerst research group on glass and liquid crystal polymer (LCP) substrates and tested at Toyota Research Institute- North America (TRI-NA). When characterized at W-band frequencies, these

  8. Magnetoactive Acoustic Metamaterials.

    Science.gov (United States)

    Yu, Kunhao; Fang, Nicholas X; Huang, Guoliang; Wang, Qiming

    2018-04-11

    Acoustic metamaterials with negative constitutive parameters (modulus and/or mass density) have shown great potential in diverse applications ranging from sonic cloaking, abnormal refraction and superlensing, to noise canceling. In conventional acoustic metamaterials, the negative constitutive parameters are engineered via tailored structures with fixed geometries; therefore, the relationships between constitutive parameters and acoustic frequencies are typically fixed to form a 2D phase space once the structures are fabricated. Here, by means of a model system of magnetoactive lattice structures, stimuli-responsive acoustic metamaterials are demonstrated to be able to extend the 2D phase space to 3D through rapidly and repeatedly switching signs of constitutive parameters with remote magnetic fields. It is shown for the first time that effective modulus can be reversibly switched between positive and negative within controlled frequency regimes through lattice buckling modulated by theoretically predicted magnetic fields. The magnetically triggered negative-modulus and cavity-induced negative density are integrated to achieve flexible switching between single-negative and double-negative. This strategy opens promising avenues for remote, rapid, and reversible modulation of acoustic transportation, refraction, imaging, and focusing in subwavelength regimes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Modeling of causality with metamaterials

    International Nuclear Information System (INIS)

    Smolyaninov, Igor I

    2013-01-01

    Hyperbolic metamaterials may be used to model a 2 + 1-dimensional Minkowski space–time in which the role of time is played by one of the spatial coordinates. When a metamaterial is built and illuminated with a coherent extraordinary laser beam, the stationary pattern of light propagation inside the metamaterial may be treated as a collection of particle world lines, which represents a complete ‘history’ of this 2 + 1-dimensional space–time. While this model may be used to build interesting space–time analogs, such as metamaterial ‘black holes’ and a metamaterial ‘big bang’, it lacks causality: since light inside the metamaterial may propagate back and forth along the ‘timelike’ spatial coordinate, events in the ‘future’ may affect events in the ‘past’. Here we demonstrate that a more sophisticated metamaterial model may fix this deficiency via breaking the mirror and temporal (PT) symmetries of the original model and producing one-way propagation along the ‘timelike’ spatial coordinate. The resulting 2 + 1-dimensional Minkowski space–time appears to be causal. This scenario may be considered as a metamaterial model of the Wheeler–Feynman absorber theory of causality. (paper)

  10. 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

  11. Wireless EEG System Achieving High Throughput and Reduced Energy Consumption Through Lossless and Near-Lossless Compression.

    Science.gov (United States)

    Alvarez, Guillermo Dufort Y; Favaro, Federico; Lecumberry, Federico; Martin, Alvaro; Oliver, Juan P; Oreggioni, Julian; Ramirez, Ignacio; Seroussi, Gadiel; Steinfeld, Leonardo

    2018-02-01

    This work presents a wireless multichannel electroencephalogram (EEG) recording system featuring lossless and near-lossless compression of the digitized EEG signal. Two novel, low-complexity, efficient compression algorithms were developed and tested in a low-power platform. The algorithms were tested on six public EEG databases comparing favorably with the best compression rates reported up to date in the literature. In its lossless mode, the platform is capable of encoding and transmitting 59-channel EEG signals, sampled at 500 Hz and 16 bits per sample, at a current consumption of 337 A per channel; this comes with a guarantee that the decompressed signal is identical to the sampled one. The near-lossless mode allows for significant energy savings and/or higher throughputs in exchange for a small guaranteed maximum per-sample distortion in the recovered signal. Finally, we address the tradeoff between computation cost and transmission savings by evaluating three alternatives: sending raw data, or encoding with one of two compression algorithms that differ in complexity and compression performance. We observe that the higher the throughput (number of channels and sampling rate) the larger the benefits obtained from compression.

  12. Lossy to lossless object-based coding of 3-D MRI data.

    Science.gov (United States)

    Menegaz, Gloria; Thiran, Jean-Philippe

    2002-01-01

    We propose a fully three-dimensional (3-D) object-based coding system exploiting the diagnostic relevance of the different regions of the volumetric data for rate allocation. The data are first decorrelated via a 3-D discrete wavelet transform. The implementation via the lifting steps scheme allows to map integer-to-integer values, enabling lossless coding, and facilitates the definition of the object-based inverse transform. The coding process assigns disjoint segments of the bitstream to the different objects, which can be independently accessed and reconstructed at any up-to-lossless quality. Two fully 3-D coding strategies are considered: embedded zerotree coding (EZW-3D) and multidimensional layered zero coding (MLZC), both generalized for region of interest (ROI)-based processing. In order to avoid artifacts along region boundaries, some extra coefficients must be encoded for each object. This gives rise to an overheading of the bitstream with respect to the case where the volume is encoded as a whole. The amount of such extra information depends on both the filter length and the decomposition depth. The system is characterized on a set of head magnetic resonance images. Results show that MLZC and EZW-3D have competitive performances. In particular, the best MLZC mode outperforms the others state-of-the-art techniques on one of the datasets for which results are available in the literature.

  13. Low-cost metamaterial-on-paper chemical sensor.

    Science.gov (United States)

    Sadeqi, Aydin; Nejad, Hojatollah Rezaei; Sonkusale, Sameer

    2017-07-10

    We present a disposable low cost paper-based metamaterial for sensing liquids based on their dielectric properties. The sensor is based on resonance shift due to the change in the effective capacitance of each resonator in the metamaterial array. Key novelty in the design is the implementation of metamaterial on low cost and ubiquitous paper substrate. This metamaterial-on-paper sensor is fabricated in a totally cleanroom-free process using wax printing and screen printing. Wax patterning of paper enables creation of microfluidic channels such that liquid analytes can be delivered to each metamaterial unit cell for sensing. Screen printing is used to implement disc shaped resonator unit cells. We demonstrate sensing of liquids: Oil, methanol, glycerol and water each showing an average resonance frequency shift of 1.12 (9.6%), 4.12 (35.4%), 8.76 (75.3%) and 11.63 GHz (100%) around the center frequency of around 94 GHz respectively. Being label-free, this approach can be expanded to sense other liquids based on their dielectric constants.

  14. Tunable Multilayer Graphene Metamaterials for Terahertz/Infrared Waveguide Modulators

    DEFF Research Database (Denmark)

    Khromova, Irina; Andryieuski, Andrei; Lavrinenko, Andrei

    regimes of multilayer graphene-dielectric artificial metamaterials. The interplay between interband and intraband transitions in graphene allows converting the structure into a transparent and/or electromagnetically dense artificial medium. 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 and tunable bandpass filtering. The absence of scattered radiation enables dense...... the latter to shift its central frequency by 1:25% per every meV graphene Fermi energy change. We believe that graphene-dielectric multilayer metamaterials will constitute the functional platform for THz-IR waveguide-integrated devices....

  15. "Slow" light in metamaterials

    OpenAIRE

    Papasimakis, Nikitas; Fedotov, Vassili A.; Zheludev, Nikolay I.; Prosvirnin, Sergey L.

    2007-01-01

    We demonstrate that propagation of microwave pulses can be significantly affected by the presence of a planar fish-scale metamaterial, which is at least 30 times thinner than the wavelength. In the resonant band of the fish-scale structure, a spectrally narrow pulse (18 ns) can be significantly delayed (by 5.6 ns) as if propagating through an 84 cm thick dielectric (epsilon=3.77), while a short pulse (220 ps) will split in two roughly equal pulses propagating with subluminal and superluminal ...

  16. Real-time lossless compression of depth streams

    KAUST Repository

    Schneider, Jens

    2017-08-17

    Various examples are provided for lossless compression of data streams. In one example, a Z-lossless (ZLS) compression method includes generating compacted depth information by condensing information of a depth image and a compressed binary representation of the depth image using histogram compaction and decorrelating the compacted depth information to produce bitplane slicing of residuals by spatial prediction. In another example, an apparatus includes imaging circuitry that can capture one or more depth images and processing circuitry that can generate compacted depth information by condensing information of a captured depth image and a compressed binary representation of the captured depth image using histogram compaction; decorrelate the compacted depth information to produce bitplane slicing of residuals by spatial prediction; and generate an output stream based upon the bitplane slicing.

  17. Lossless Image Compression Based on Multiple-Tables Arithmetic Coding

    Directory of Open Access Journals (Sweden)

    Rung-Ching Chen

    2009-01-01

    Full Text Available This paper is intended to present a lossless image compression method based on multiple-tables arithmetic coding (MTAC method to encode a gray-level image f. First, the MTAC method employs a median edge detector (MED to reduce the entropy rate of f. The gray levels of two adjacent pixels in an image are usually similar. A base-switching transformation approach is then used to reduce the spatial redundancy of the image. The gray levels of some pixels in an image are more common than those of others. Finally, the arithmetic encoding method is applied to reduce the coding redundancy of the image. To promote high performance of the arithmetic encoding method, the MTAC method first classifies the data and then encodes each cluster of data using a distinct code table. The experimental results show that, in most cases, the MTAC method provides a higher efficiency in use of storage space than the lossless JPEG2000 does.

  18. Real-time lossless compression of depth streams

    KAUST Repository

    Schneider, Jens

    2017-01-01

    Various examples are provided for lossless compression of data streams. In one example, a Z-lossless (ZLS) compression method includes generating compacted depth information by condensing information of a depth image and a compressed binary representation of the depth image using histogram compaction and decorrelating the compacted depth information to produce bitplane slicing of residuals by spatial prediction. In another example, an apparatus includes imaging circuitry that can capture one or more depth images and processing circuitry that can generate compacted depth information by condensing information of a captured depth image and a compressed binary representation of the captured depth image using histogram compaction; decorrelate the compacted depth information to produce bitplane slicing of residuals by spatial prediction; and generate an output stream based upon the bitplane slicing.

  19. 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...

  20. Lossless medical image compression with a hybrid coder

    Science.gov (United States)

    Way, Jing-Dar; Cheng, Po-Yuen

    1998-10-01

    The volume of medical image data is expected to increase dramatically in the next decade due to the large use of radiological image for medical diagnosis. The economics of distributing the medical image dictate that data compression is essential. While there is lossy image compression, the medical image must be recorded and transmitted lossless before it reaches the users to avoid wrong diagnosis due to the image data lost. Therefore, a low complexity, high performance lossless compression schematic that can approach the theoretic bound and operate in near real-time is needed. In this paper, we propose a hybrid image coder to compress the digitized medical image without any data loss. The hybrid coder is constituted of two key components: an embedded wavelet coder and a lossless run-length coder. In this system, the medical image is compressed with the lossy wavelet coder first, and the residual image between the original and the compressed ones is further compressed with the run-length coder. Several optimization schemes have been used in these coders to increase the coding performance. It is shown that the proposed algorithm is with higher compression ratio than run-length entropy coders such as arithmetic, Huffman and Lempel-Ziv coders.

  1. 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...

  2. Perspective: Acoustic metamaterials in transition

    KAUST Repository

    Wu, Ying; Yang, Min; Sheng, Ping

    2017-01-01

    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

  3. 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.

  4. Homogenization of resonant chiral metamaterials

    OpenAIRE

    Andryieuski, Andrei; Menzel, Christoph; Rockstuhl, Carsten; Malureanu, Radu; Lederer, Falk; Lavrinenko, Andrei

    2010-01-01

    Homogenization of metamaterials is a crucial issue as it allows to describe their optical response in terms of effective wave parameters as e.g. propagation constants. In this paper we consider the possible homogenization of chiral metamaterials. We show that for meta-atoms of a certain size a critical density exists above which increasing coupling between neighboring meta-atoms prevails a reasonable homogenization. On the contrary, a dilution in excess will induce features reminiscent to pho...

  5. Science meets magic: photonic metamaterials

    Science.gov (United States)

    Ozbay, Ekmel

    2012-05-01

    The word "magic" is usually associated with movies, fiction, children stories, etc. but seldom with the natural sciences. Recent advances in metamaterials have changed this notion, in which we can now speak of "almost magical" properties that scientists could only dream about only a decade ago. In this article, we review some of the recent "almost magical" progress in the field of meta-materials.

  6. Critical opalescence in hyperbolic metamaterials

    International Nuclear Information System (INIS)

    Smolyaninov, Igor I

    2011-01-01

    Hyperbolic metamaterials in which the dielectric component exhibits critical opalescence have been considered. It appears that fluctuations of the effective refractive index in these materials are strongly enhanced and so 'virtual electromagnetic black holes' may appear as a result of these fluctuations. Therefore, the behaviour of 'optical space' inside hyperbolic metamaterials looks somewhat similar to the behaviour of real physical space-time on the Planck scale

  7. Critical opalescence in hyperbolic metamaterials

    Science.gov (United States)

    Smolyaninov, Igor I.

    2011-12-01

    Hyperbolic metamaterials in which the dielectric component exhibits critical opalescence have been considered. It appears that fluctuations of the effective refractive index in these materials are strongly enhanced and so 'virtual electromagnetic black holes' may appear as a result of these fluctuations. Therefore, the behaviour of 'optical space' inside hyperbolic metamaterials looks somewhat similar to the behaviour of real physical space-time on the Planck scale.

  8. 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

  9. Deformable wire array: fiber drawn tunable metamaterials

    DEFF Research Database (Denmark)

    Fleming, Simon; Stefani, Alessio; Tang, Xiaoli

    2017-01-01

    By fiber drawing we fabricate a wire array metamaterial, the structure of which can be actively modified. The plasma frequency can be tuned by 50% by compressing the metamaterial; recovers when released and the process can be repeated.......By fiber drawing we fabricate a wire array metamaterial, the structure of which can be actively modified. The plasma frequency can be tuned by 50% by compressing the metamaterial; recovers when released and the process can be repeated....

  10. 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...

  11. 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.

  12. 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...

  13. Electro-magnetostatic homogenization of bianisotropic metamaterials

    OpenAIRE

    Fietz, Chris

    2012-01-01

    We apply the method of asymptotic homogenization to metamaterials with microscopically bianisotropic inclusions to calculate a full set of constitutive parameters in the long wavelength limit. Two different implementations of electromagnetic asymptotic homogenization are presented. We test the homogenization procedure on two different metamaterial examples. Finally, the analytical solution for long wavelength homogenization of a one dimensional metamaterial with microscopically bi-isotropic i...

  14. Enhanced acoustic sensing through wave compression and pressure amplification in anisotropic metamaterials.

    Science.gov (United States)

    Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao

    2014-10-15

    Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental pressure detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong wave compression effect that renders direct amplification of pressure fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications.

  15. Miniaturized dual-band antenna array with double-negative (DNG) metamaterial for wireless applications

    Science.gov (United States)

    Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Vandenbosch, Guy A. E.; Narbudowicz, Adam

    2017-01-01

    A miniaturized dual-band antenna array using a negative index metamaterial is presented for WiMAX, LTE, and WLAN applications. This left-handed metamaterial plane is located behind the antenna array, and its unit cell is a combination of split-ring resonator, square electric ring resonator, and rectangular electrical coupled resonator. This enables the achievement of a metamaterial structure exhibiting both negative permittivity and permeability, which results in antenna size miniaturization, efficiency, and gain enhancement. Moreover, the proposed metamaterial antenna has realized dual-band operating frequencies compared to a single frequency for normal antenna. The measured reflection coefficient (S11) shows a 50.25% bandwidth in the lower band (from 2.119 to 3.058 GHz) and 4.27% in the upper band (from 5.058 to 5.276 GHz). Radiation efficiency obtained in the lower and upper band are >95 and 80%, respectively.

  16. Large-scale fabrication of achiral plasmonic metamaterials with giant chiroptical response

    Directory of Open Access Journals (Sweden)

    Morten Slyngborg

    2016-06-01

    Full Text Available A variety of extrinsic chiral metamaterials were fabricated by a combination of self-ordering anodic oxidation of aluminum foil, nanoimprint lithography and glancing angle deposition. All of these techniques are scalable and pose a significant improvement to standard metamaterial fabrication techniques. Different interpore distances and glancing angle depositions enable the plasmonic resonance wavelength to be tunable in the range from UVA to IR. These extrinsic chiral metamaterials only exhibit significant chiroptical response at non-normal angles of incidence. This intrinsic property enables the probing of both enantoimeric structures on the same sample, by inverting the tilt of the sample relative to the normal angle. In biosensor applications this allows for more precise, cheap and commercialized devices. As a proof of concept two different molecules were used to probe the sensitivity of the metamaterials. These proved the applicability to sense proteins through non-specific adsorption on the metamaterial surface or through functionalized surfaces to increase the sensing sensitivity. Besides increasing the sensing sensitivity, these metamaterials may also be commercialized and find applications in surface-enhanced IR spectroscopy, terahertz generation and terahertz circular dichroism spectroscopy.

  17. A two-dimensional uniplanar transmission-line metamaterial with a negative index of refraction

    International Nuclear Information System (INIS)

    Elek, Francis; Eleftheriades, George V

    2005-01-01

    A uniplanar transmission-line (TL) network has been loaded with lumped elements (chip or printed), enabling one to achieve a two-dimensional (2D) uniplanar negative-refractive-index (NRI) metamaterial. The metamaterial consists of a 2D array of unit cells, composed of TL sections connected in series and loaded in a specified manner. The unit cell dimensions can be designed to be much smaller than the operating wavelength, enabling one to identify the structure as an effective medium, with a negative index of refraction. This NRI metamaterial supports transverse electric (TE) waves, as opposed to related previous work on NRI-TL media that supported transverse magnetic (TM) waves. The dispersion characteristics are calculated using a simple, fast 2D loaded TL model with periodic (Bloch) boundary conditions. Subsequently the dispersion relation is simplified in the homogeneous limit, thus allowing one to identify effective permittivities and permeabilities, which are shown to be simultaneously negative. Simulations demonstrating the negative refraction of a plane wave on an interface between such a NRI uniplanar metamaterial and a commensurate positive-refractive-index (PRI) metamaterial verify the validity of the proposed concept and theory. A fully printed unit cell is presented at microwave frequencies (∼10 GHz) along with a prescription for synthesizing an isotropic 3D transmission line NRI metamaterial based on this unit cell

  18. Highly-stretchable 3D-architected Mechanical Metamaterials

    Science.gov (United States)

    Jiang, Yanhui; Wang, Qiming

    2016-09-01

    Soft materials featuring both 3D free-form architectures and high stretchability are highly desirable for a number of engineering applications ranging from cushion modulators, soft robots to stretchable electronics; however, both the manufacturing and fundamental mechanics are largely elusive. Here, we overcome the manufacturing difficulties and report a class of mechanical metamaterials that not only features 3D free-form lattice architectures but also poses ultrahigh reversible stretchability (strain > 414%), 4 times higher than that of the existing counterparts with the similar complexity of 3D architectures. The microarchitected metamaterials, made of highly stretchable elastomers, are realized through an additive manufacturing technique, projection microstereolithography, and its postprocessing. With the fabricated metamaterials, we reveal their exotic mechanical behaviors: Under large-strain tension, their moduli follow a linear scaling relationship with their densities regardless of architecture types, in sharp contrast to the architecture-dependent modulus power-law of the existing engineering materials; under large-strain compression, they present tunable negative-stiffness that enables ultrahigh energy absorption efficiencies. To harness their extraordinary stretchability and microstructures, we demonstrate that the metamaterials open a number of application avenues in lightweight and flexible structure connectors, ultraefficient dampers, 3D meshed rehabilitation structures and stretchable electronics with designed 3D anisotropic conductivity.

  19. Spiraling Light with Magnetic Metamaterial Quarter-Wave Turbines.

    Science.gov (United States)

    Zeng, Jinwei; Luk, Ting S; Gao, Jie; Yang, Xiaodong

    2017-09-19

    Miniaturized quarter-wave plate devices empower spin to orbital angular momentum conversion and vector polarization formation, which serve as bridges connecting conventional optical beam and structured light. Enabling the manipulability of additional dimensions as the complex polarization and phase of light, quarter-wave plate devices are essential for exploring a plethora of applications based on orbital angular momentum or vector polarization, such as optical sensing, holography, and communication. Here we propose and demonstrate the magnetic metamaterial quarter-wave turbines at visible wavelength to produce radially and azimuthally polarized vector vortices from circularly polarized incident beam. The magnetic metamaterials function excellently as quarter-wave plates at single wavelength and maintain the quarter-wave phase retardation in broadband, while the turbine blades consist of multiple polar sections, each of which contains homogeneously oriented magnetic metamaterial gratings near azimuthal or radial directions to effectively convert circular polarization to linear polarization and induce phase shift under Pancharatnum-Berry's phase principle. The perspective concept of multiple polar sections of magnetic metamaterials can extend to other analogous designs in the strongly coupled nanostructures to accomplish many types of light phase-polarization manipulation and structured light conversion in the desired manner.

  20. Zero refractive index in time-Floquet acoustic metamaterials

    Science.gov (United States)

    Koutserimpas, Theodoros T.; Fleury, Romain

    2018-03-01

    New scientific investigations of artificially structured materials and experiments have exhibited wave manipulation to the extreme. In particular, zero refractive index metamaterials have been on the front line of wave physics research for their unique wave manipulation properties and application potentials. Remarkably, in such exotic materials, time-harmonic fields have an infinite wavelength and do not exhibit any spatial variations in their phase distribution. This unique feature can be achieved by forcing a Dirac cone to the center of the Brillouin zone ( Γ point), as previously predicted and experimentally demonstrated in time-invariant metamaterials by means of accidental degeneracy between three different modes. In this article, we propose a different approach that enables true conical dispersion at Γ with twofold degeneracy and generates zero index properties. We break time-reversal symmetry and exploit a time-Floquet modulation scheme to demonstrate a time-Floquet acoustic metamaterial with zero refractive index. This behavior, predicted using stroboscopic analysis, is confirmed by full-wave finite element simulations. Our results establish the relevance of time-Floquet metamaterials as a novel reconfigurable platform for wave control.

  1. New procedures to evaluate visually lossless compression for display systems

    Science.gov (United States)

    Stolitzka, Dale F.; Schelkens, Peter; Bruylants, Tim

    2017-09-01

    Visually lossless image coding in isochronous display streaming or plesiochronous networks reduces link complexity and power consumption and increases available link bandwidth. A new set of codecs developed within the last four years promise a new level of coding quality, but require new techniques that are sufficiently sensitive to the small artifacts or color variations induced by this new breed of codecs. This paper begins with a summary of the new ISO/IEC 29170-2, a procedure for evaluation of lossless coding and reports the new work by JPEG to extend the procedure in two important ways, for HDR content and for evaluating the differences between still images, panning images and image sequences. ISO/IEC 29170-2 relies on processing test images through a well-defined process chain for subjective, forced-choice psychophysical experiments. The procedure sets an acceptable quality level equal to one just noticeable difference. Traditional image and video coding evaluation techniques, such as, those used for television evaluation have not proven sufficiently sensitive to the small artifacts that may be induced by this breed of codecs. In 2015, JPEG received new requirements to expand evaluation of visually lossless coding for high dynamic range images, slowly moving images, i.e., panning, and image sequences. These requirements are the basis for new amendments of the ISO/IEC 29170-2 procedures described in this paper. These amendments promise to be highly useful for the new content in television and cinema mezzanine networks. The amendments passed the final ballot in April 2017 and are on track to be published in 2018.

  2. Lossless compression of waveform data for efficient storage and transmission

    International Nuclear Information System (INIS)

    Stearns, S.D.; Tan, Li Zhe; Magotra, Neeraj

    1993-01-01

    Compression of waveform data is significant in many engineering and research areas since it can be used to alleviate data storage and transmission bandwidth. For example, seismic data are widely recorded and transmitted so that analysis can be performed on large amounts of data for numerous applications such as petroleum exploration, determination of the earth's core structure, seismic event detection and discrimination of underground nuclear explosions, etc. This paper describes a technique for lossless wave form data compression. The technique consists of two stages. The first stage is a modified form of linear prediction with discrete coefficients and the second stage is bi-level sequence coding. The linear predictor generates an error or residue sequence in a way such that exact reconstruction of the original data sequence can be accomplished with a simple algorithm. The residue sequence is essentially white Gaussian with seismic or other similar waveform data. Bi-level sequence coding, in which two sample sizes are chosen and the residue sequence is encoded into subsequences that alternate from one level to the other, further compresses the residue sequence. The principal feature of the two-stage data compression algorithm is that it is lossless, that is, it allows exact, bit-for-bit recovery of the original data sequence. The performance of the lossless compression algorithm at each stage is analyzed. The advantages of using bi-level sequence coding in the second stage are its simplicity of implementation, its effectiveness on data with large amplitude variations, and its near-optimal performance in encoding Gaussian sequences. Applications of the two-stage technique to typical seismic data indicates that an average number of compressed bits per sample close to the lower bound is achievable in practical situations

  3. Lossy/lossless coding of bi-level images

    DEFF Research Database (Denmark)

    Martins, Bo; Forchhammer, Søren

    1997-01-01

    Summary form only given. We present improvements to a general type of lossless, lossy, and refinement coding of bi-level images (Martins and Forchhammer, 1996). Loss is introduced by flipping pixels. The pixels are coded using arithmetic coding of conditional probabilities obtained using a template...... as is known from JBIG and proposed in JBIG-2 (Martins and Forchhammer). Our new state-of-the-art results are obtained using the more general free tree instead of a template. Also we introduce multiple refinement template coding. The lossy algorithm is analogous to the greedy `rate...

  4. Lossless droplet transfer of droplet-based microfluidic analysis

    Science.gov (United States)

    Kelly, Ryan T [West Richland, WA; Tang, Keqi [Richland, WA; Page, Jason S [Kennewick, WA; Smith, Richard D [Richland, WA

    2011-11-22

    A transfer structure for droplet-based microfluidic analysis is characterized by a first conduit containing a first stream having at least one immiscible droplet of aqueous material and a second conduit containing a second stream comprising an aqueous fluid. The interface between the first conduit and the second conduit can define a plurality of apertures, wherein the apertures are sized to prevent exchange of the first and second streams between conduits while allowing lossless transfer of droplets from the first conduit to the second conduit through contact between the first and second streams.

  5. The CCSDS Lossless Data Compression Algorithm for Space Applications

    Science.gov (United States)

    Yeh, Pen-Shu; Day, John H. (Technical Monitor)

    2001-01-01

    In the late 80's, when the author started working at the Goddard Space Flight Center (GSFC) for the National Aeronautics and Space Administration (NASA), several scientists there were in the process of formulating the next generation of Earth viewing science instruments, the Moderate Resolution Imaging Spectroradiometer (MODIS). The instrument would have over thirty spectral bands and would transmit enormous data through the communications channel. This was when the author was assigned the task of investigating lossless compression algorithms for space implementation to compress science data in order to reduce the requirement on bandwidth and storage.

  6. Scalable, ultra-resistant structural colors based on network metamaterials

    KAUST Repository

    Galinski, Henning

    2017-05-05

    Structural colors have drawn wide attention for their potential as a future printing technology for various applications, ranging from biomimetic tissues to adaptive camouflage materials. However, an efficient approach to realize robust colors with a scalable fabrication technique is still lacking, hampering the realization of practical applications with this platform. Here, we develop a new approach based on large-scale network metamaterials that combine dealloyed subwavelength structures at the nanoscale with lossless, ultra-thin dielectric coatings. By using theory and experiments, we show how subwavelength dielectric coatings control a mechanism of resonant light coupling with epsilon-near-zero regions generated in the metallic network, generating the formation of saturated structural colors that cover a wide portion of the spectrum. Ellipsometry measurements support the efficient observation of these colors, even at angles of 70°. The network-like architecture of these nanomaterials allows for high mechanical resistance, which is quantified in a series of nano-scratch tests. With such remarkable properties, these metastructures represent a robust design technology for real-world, large-scale commercial applications.

  7. Distributed Source Coding Techniques for Lossless Compression of Hyperspectral Images

    Directory of Open Access Journals (Sweden)

    Barni Mauro

    2007-01-01

    Full Text Available This paper deals with the application of distributed source coding (DSC theory to remote sensing image compression. Although DSC exhibits a significant potential in many application fields, up till now the results obtained on real signals fall short of the theoretical bounds, and often impose additional system-level constraints. The objective of this paper is to assess the potential of DSC for lossless image compression carried out onboard a remote platform. We first provide a brief overview of DSC of correlated information sources. We then focus on onboard lossless image compression, and apply DSC techniques in order to reduce the complexity of the onboard encoder, at the expense of the decoder's, by exploiting the correlation of different bands of a hyperspectral dataset. Specifically, we propose two different compression schemes, one based on powerful binary error-correcting codes employed as source codes, and one based on simpler multilevel coset codes. The performance of both schemes is evaluated on a few AVIRIS scenes, and is compared with other state-of-the-art 2D and 3D coders. Both schemes turn out to achieve competitive compression performance, and one of them also has reduced complexity. Based on these results, we highlight the main issues that are still to be solved to further improve the performance of DSC-based remote sensing systems.

  8. Interband coding extension of the new lossless JPEG standard

    Science.gov (United States)

    Memon, Nasir D.; Wu, Xiaolin; Sippy, V.; Miller, G.

    1997-01-01

    Due to the perceived inadequacy of current standards for lossless image compression, the JPEG committee of the International Standards Organization (ISO) has been developing a new standard. A baseline algorithm, called JPEG-LS, has already been completed and is awaiting approval by national bodies. The JPEG-LS baseline algorithm despite being simple is surprisingly efficient, and provides compression performance that is within a few percent of the best and more sophisticated techniques reported in the literature. Extensive experimentations performed by the authors seem to indicate that an overall improvement by more than 10 percent in compression performance will be difficult to obtain even at the cost of great complexity; at least not with traditional approaches to lossless image compression. However, if we allow inter-band decorrelation and modeling in the baseline algorithm, nearly 30 percent improvement in compression gains for specific images in the test set become possible with a modest computational cost. In this paper we propose and investigate a few techniques for exploiting inter-band correlations in multi-band images. These techniques have been designed within the framework of the baseline algorithm, and require minimal changes to the basic architecture of the baseline, retaining its essential simplicity.

  9. Low complexity lossless compression of underwater sound recordings.

    Science.gov (United States)

    Johnson, Mark; Partan, Jim; Hurst, Tom

    2013-03-01

    Autonomous listening devices are increasingly used to study vocal aquatic animals, and there is a constant need to record longer or with greater bandwidth, requiring efficient use of memory and battery power. Real-time compression of sound has the potential to extend recording durations and bandwidths at the expense of increased processing operations and therefore power consumption. Whereas lossy methods such as MP3 introduce undesirable artifacts, lossless compression algorithms (e.g., flac) guarantee exact data recovery. But these algorithms are relatively complex due to the wide variety of signals they are designed to compress. A simpler lossless algorithm is shown here to provide compression factors of three or more for underwater sound recordings over a range of noise environments. The compressor was evaluated using samples from drifting and animal-borne sound recorders with sampling rates of 16-240 kHz. It achieves >87% of the compression of more-complex methods but requires about 1/10 of the processing operations resulting in less than 1 mW power consumption at a sampling rate of 192 kHz on a low-power microprocessor. The potential to triple recording duration with a minor increase in power consumption and no loss in sound quality may be especially valuable for battery-limited tags and robotic vehicles.

  10. LFQC: a lossless compression algorithm for FASTQ files

    Science.gov (United States)

    Nicolae, Marius; Pathak, Sudipta; Rajasekaran, Sanguthevar

    2015-01-01

    Motivation: Next Generation Sequencing (NGS) technologies have revolutionized genomic research by reducing the cost of whole genome sequencing. One of the biggest challenges posed by modern sequencing technology is economic storage of NGS data. Storing raw data is infeasible because of its enormous size and high redundancy. In this article, we address the problem of storage and transmission of large FASTQ files using innovative compression techniques. Results: We introduce a new lossless non-reference based FASTQ compression algorithm named Lossless FASTQ Compressor. We have compared our algorithm with other state of the art big data compression algorithms namely gzip, bzip2, fastqz (Bonfield and Mahoney, 2013), fqzcomp (Bonfield and Mahoney, 2013), Quip (Jones et al., 2012), DSRC2 (Roguski and Deorowicz, 2014). This comparison reveals that our algorithm achieves better compression ratios on LS454 and SOLiD datasets. Availability and implementation: The implementations are freely available for non-commercial purposes. They can be downloaded from http://engr.uconn.edu/rajasek/lfqc-v1.1.zip. Contact: rajasek@engr.uconn.edu PMID:26093148

  11. 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...

  12. A programmable nonlinear acoustic metamaterial

    Directory of Open Access Journals (Sweden)

    Tianzhi Yang

    2017-09-01

    Full Text Available Acoustic metamaterials with specifically designed lattices can manipulate acoustic/elastic waves in unprecedented ways. Whereas there are many studies that focus on passive linear lattice, with non-reconfigurable structures. In this letter, we present the design, theory and experimental demonstration of an active nonlinear acoustic metamaterial, the dynamic properties of which can be modified instantaneously with reversibility. By incorporating active and nonlinear elements in a single unit cell, a real-time tunability and switchability of the band gap is achieved. In addition, we demonstrate a dynamic “editing” capability for shaping transmission spectra, which can be used to create the desired band gap and resonance. This feature is impossible to achieve in passive metamaterials. These advantages demonstrate the versatility of the proposed device, paving the way toward smart acoustic devices, such as logic elements, diode and transistor.

  13. Effects of Metamaterial Slabs Applied to Wireless Power Transfer at 13.56 MHz

    Directory of Open Access Journals (Sweden)

    Gunyoung Kim

    2015-01-01

    Full Text Available This paper analyzes the effects of a metamaterial slab (or a practical “perfect lens” with negative permeability applied to a two loop magnetically coupled wireless power transfer (WPT system at 13.56 MHz, based on theory, full-wave electromagnetic- (EM- simulations, and measurements. When using lossless slabs with ideal negative permeability in EM-simulations, the WPT efficiencies have been found to be enhanced close to 100% due to the magnetic field focusing. For the case of using a realistic slab made of ring resonators (RR μr=-1-j0.23 with s/d=0.5 (s: slab width, d: distance between the transmitting and receiving loops, the WPT efficiency has been found to significantly decrease to about 20%, even lower than that of a free space case (32% due to the heavy power absorption in the slab. However, some efficiency enhancement can be achieved when s/d is optimized between 0.1 and 0.3. Overall, the significant enhancement of efficiencies when using a lossless slab becomes moderate or only marginal when employing a realistic slab.

  14. 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.

  15. 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.

  16. A Brief Review on Metamaterial-Based Vacuum Electronics for Terahertz and Microwave Science and Technology

    Science.gov (United States)

    Matsui, Tatsunosuke

    2017-09-01

    Metamaterials, which enable us to realize novel physical effects that cannot be achieved using natural materials, have been extensively studied in recent years and significant progress has been made, especially in the field of optics. This game-changing concept has also initiated a rich variety of research activity in vacuum electronics. Here we review the recent development of metamaterial-based vacuum electronics for terahertz (THz) and microwave science and technology. The reversed Cherenkov radiation (RCR) in double-negative (DNG) metamaterials predicted by Veselago back in the 1960s has been experimentally verified in the microwave frequency range by utilizing specially designed DNG metamaterials. The interaction of an electron beam (e-beam) with DNG metamaterials may lead to the realization of novel applications such as microwave and THz radiation sources, accelerators, and even the visualization of invisibility cloaks. Smith-Purcell radiation (SPR) has recently received renewed interest owing to the development of metamaterials and the concept of spoof surface plasmon polaritons, as discussed in this review, and recent results on e-beam-induced directional and wide-band THz radiation with sharp multiple peaks from a graded grating, as well as directional and monochromatic special SPR and their possible application to THz orotron devices, are also reviewed.

  17. 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.

  18. Multiscale mechanics of dynamical metamaterials

    NARCIS (Netherlands)

    Geers, M.G.D.; Kouznetsova, V.; Sridhar, A.; Krushynska, A.; Kleiber, M.; Burczynski, T.; Wilde, K.; Gorski, J.; Winkelmann, K.; Smakosz, L.

    2016-01-01

    This contribution focuses on the computational multi-scale solution of wave propagation phenomena in dynamic metamaterials. Taking the Bloch-Floquet solution for the standard elastic case as a point of departure, an extended scheme is presented to solve for heterogeneous visco-elastic materials. The

  19. Choice of word length in the design of a specialized hardware for lossless wavelet compression of medical images

    Science.gov (United States)

    Urriza, Isidro; Barragan, Luis A.; Artigas, Jose I.; Garcia, Jose I.; Navarro, Denis

    1997-11-01

    Image compression plays an important role in the archiving and transmission of medical images. Discrete cosine transform (DCT)-based compression methods are not suitable for medical images because of block-like image artifacts that could mask or be mistaken for pathology. Wavelet transforms (WTs) are used to overcome this problem. When implementing WTs in hardware, finite precision arithmetic introduces quantization errors. However, lossless compression is usually required in the medical image field. Thus, the hardware designer must look for the optimum register length that, while ensuring the lossless accuracy criteria, will also lead to a high-speed implementation with small chip area. In addition, wavelet choice is a critical issue that affects image quality as well as system design. We analyze the filters best suited to image compression that appear in the literature. For them, we obtain the maximum quantization errors produced in the calculation of the WT components. Thus, we deduce the minimum word length required for the reconstructed image to be numerically identical to the original image. The theoretical results are compared with experimental results obtained from algorithm simulations on random test images. These results enable us to compare the hardware implementation cost of the different filter banks. Moreover, to reduce the word length, we have analyzed the case of increasing the integer part of the numbers while maintaining constant the word length when the scale increases.

  20. 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.

  1. Development and evaluation of a novel lossless image compression method (AIC: artificial intelligence compression method) using neural networks as artificial intelligence

    International Nuclear Information System (INIS)

    Fukatsu, Hiroshi; Naganawa, Shinji; Yumura, Shinnichiro

    2008-01-01

    This study was aimed to validate the performance of a novel image compression method using a neural network to achieve a lossless compression. The encoding consists of the following blocks: a prediction block; a residual data calculation block; a transformation and quantization block; an organization and modification block; and an entropy encoding block. The predicted image is divided into four macro-blocks using the original image for teaching; and then redivided into sixteen sub-blocks. The predicted image is compared to the original image to create the residual image. The spatial and frequency data of the residual image are compared and transformed. Chest radiography, computed tomography (CT), magnetic resonance imaging, positron emission tomography, radioisotope mammography, ultrasonography, and digital subtraction angiography images were compressed using the AIC lossless compression method; and the compression rates were calculated. The compression rates were around 15:1 for chest radiography and mammography, 12:1 for CT, and around 6:1 for other images. This method thus enables greater lossless compression than the conventional methods. This novel method should improve the efficiency of handling of the increasing volume of medical imaging data. (author)

  2. 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.

  3. Multifunctional metamaterial designs for antenna applications

    OpenAIRE

    Ferrer González, Pere Josep

    2015-01-01

    Premi Extraordinari de Doctorat, promoció 2014-2015. Àmbit d'Enginyeria de les TIC Over the last decades, Metamaterials (MTMs) have caught the attention of the scientific community. Metamaterials are basically artificially engineered materials which can provide unusual electromagnetic properties not present in nature. Among other novel and special EM applications, such as the negative refraction index (NRI) application, Metamaterials allow the realisation of perfect magnetic conductors (PM...

  4. 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 extension from the previously much publicized microstructured optical fibers. Metamaterials can have optical properties not obtainable in naturally existing materials, including artificial anisotropy as well as graded material properties. Therefore, incorporation of metamaterial in optical fiber designs can...

  5. Electromagnetic ``black holes'' in hyperbolic metamaterials

    Science.gov (United States)

    Smolyaninov, Igor

    2013-03-01

    We demonstrate that spatial variations of the dielectric tensor components in a hyperbolic metamaterial may lead to formation of electromagnetic ``black holes'' inside this metamaterial. Similar to real black holes, horizon area of the electromagnetic ``black holes'' is quantized in units of the effective ``Planck scale'' squared. Potential experimental realizations of such electromagnetic ``black holes'' will be considered. For example, this situation may be realized in a hyperbolic metamaterial in which the dielectric component exhibits critical opalescence.

  6. 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.

  7. Selectively Lossy, Lossless, and/or Error Robust Data Compression Method

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Lossless compression techniques provide efficient compression of hyperspectral satellite data. The present invention combines the advantages of a clustering with...

  8. Mode-dependent templates and scan order for H.264/AVC-based intra lossless coding.

    Science.gov (United States)

    Gu, Zhouye; Lin, Weisi; Lee, Bu-Sung; Lau, Chiew Tong; Sun, Ming-Ting

    2012-09-01

    In H.264/advanced video coding (AVC), lossless coding and lossy coding share the same entropy coding module. However, the entropy coders in the H.264/AVC standard were original designed for lossy video coding and do not yield adequate performance for lossless video coding. In this paper, we analyze the problem with the current lossless coding scheme and propose a mode-dependent template (MD-template) based method for intra lossless coding. By exploring the statistical redundancy of the prediction residual in the H.264/AVC intra prediction modes, more zero coefficients are generated. By designing a new scan order for each MD-template, the scanned coefficients sequence fits the H.264/AVC entropy coders better. A fast implementation algorithm is also designed. With little computation increase, experimental results confirm that the proposed fast algorithm achieves about 7.2% bit saving compared with the current H.264/AVC fidelity range extensions high profile.

  9. Lossy/Lossless Floating/Grounded Inductance Simulation Using One DDCC

    Directory of Open Access Journals (Sweden)

    M. A. Ibrahim

    2012-04-01

    Full Text Available In this work, we present new topologies for realizing one lossless grounded inductor and two floating, one lossless and one lossy, inductors employing a single differential difference current conveyor (DDCC and a minimum number of passive components, two resistors, and one grounded capacitor. The floating inductors are based on ordinary dual-output differential difference current conveyor (DO-DDCC while the grounded lossless inductor is based one a modified dual-output differential difference current conveyor (MDO-DDCC. The proposed lossless floating inductor is obtained from the lossy one by employing a negative impedance converter (NIC. The non-ideality effects of the active element on the simulated inductors are investigated. To demonstrate the performance of the proposed grounded inductance simulator as an example, it is used to construct a parallel resonant circuit. SPICE simulation results are given to confirm the theoretical analysis.

  10. 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

  11. Voice Morphing Using 3D Waveform Interpolation Surfaces and Lossless Tube Area Functions

    Directory of Open Access Journals (Sweden)

    Lavner Yizhar

    2005-01-01

    Full Text Available Voice morphing is the process of producing intermediate or hybrid voices between the utterances of two speakers. It can also be defined as the process of gradually transforming the voice of one speaker to that of another. The ability to change the speaker's individual characteristics and to produce high-quality voices can be used in many applications. Examples include multimedia and video entertainment, as well as enrichment of speech databases in text-to-speech systems. In this study we present a new technique which enables production of a given number of intermediate voices or of utterances which gradually change from one voice to another. This technique is based on two components: (1 creation of a 3D prototype waveform interpolation (PWI surface from the LPC residual signal, to produce an intermediate excitation signal; (2 a representation of the vocal tract by a lossless tube area function, and an interpolation of the parameters of the two speakers. The resulting synthesized signal sounds like a natural voice lying between the two original voices.

  12. Parallel Implementation of the CCSDS 1.2.3 Standard for Hyperspectral Lossless Compression

    Directory of Open Access Journals (Sweden)

    Daniel Báscones

    2017-09-01

    Full Text Available Hyperspectral imaging is a technology which, by sensing hundreds of wavelengths per pixel, enables fine studies of the captured objects. This produces great amounts of data that require equally big storage, and compression with algorithms such as the Consultative Committee for Space Data Systems (CCSDS 1.2.3 standard is a must. However, the speed of this lossless compression algorithm is not enough in some real-time scenarios if we use a single-core processor. This is where architectures such as Field Programmable Gate Arrays (FPGAs and Graphics Processing Units (GPUs can shine best. In this paper, we present both FPGA and OpenCL implementations of the CCSDS 1.2.3 algorithm. The proposed paralellization method has been implemented on the Virtex-7 XC7VX690T, Virtex-5 XQR5VFX130 and Virtex-4 XC2VFX60 FPGAs, and on the GT440 and GT610 GPUs, and tested using hyperspectral data from NASA’s Airborne Visible Infra-Red Imaging Spectrometer (AVIRIS. Both approaches fulfill our real-time requirements. This paper attempts to shed some light on the comparison between both approaches, including other works from existing literature, explaining the trade-offs of each one.

  13. 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.

  14. 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.

  15. 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.

  16. Ion Mobility Separations of Isomers based upon Long Path Length Structures for Lossless Ion Manipulations Combined with Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Liulin [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Ibrahim, Yehia M. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Baker, Erin S. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Aly, Noor A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Hamid, Ahmed M. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Zhang, Xing [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Zheng, Xueyun [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Garimella, Sandilya V. B. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Webb, Ian K. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Prost, Spencer A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Sandoval, Jeremy A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Norheim, Randolph V. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Anderson, Gordon A. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Tolmachev, Aleksey V. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA; Smith, Richard D. [Biological Sciences Division and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Blvd Richland, WA 99352 USA

    2016-07-01

    Mass spectrometry (MS)-based multi-omic measurements, including proteomics, metabolomics, lipidomics, and glycomics, are increasingly transforming our ability to characterize and understand biological systems, but, presently have limitations due to the chemical diversity and range of abundances of biomolecules in complex samples. Advances addressing these challenges increasingly are based upon the ability to quickly separate, react and otherwise manipulate sample components for analysis by MS. Here we report on a new approach using Structures for Lossless Ion Manipulations (SLIM) to enable long serpentine path ion mobility spectrometry (IMS) separations followed by MS analyses. This approach provides previously unachieved mobility biomolecule isomer separations for biomolecular species, in conjunction with more effective ion utilization, and producing a basis for the improved characterization of very small samples.

  17. 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...

  18. 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.

  19. Effective medium theory for anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan; Wu, Ying

    2015-01-01

    -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

  20. Tunable microwave metamaterials based on ordinary water

    DEFF Research Database (Denmark)

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

    2017-01-01

    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...

  1. Circuit QED with hybrid metamaterial transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Ruloff, Stefan; Taketani, Bruno; Wilhelm, Frank [Theoretical Physics, Universitaet des Saarlandes, Saarbruecken (Germany)

    2016-07-01

    We're working on the theory of metamaterials providing some interesting results. The negative refraction index causes an opposite orientation of the wave vector k and the Poynting vector S of the travelling waves. Hence the metamaterial has a falling dispersion relation ∂ω(k)/∂k < 0 implying that low frequencies correspond to short wavelengths. Metamaterials are simulated by left-handed transmission lines consisting of discrete arrays of series capacitors and parallel inductors to ground. Unusual physics arises when right-and left-handed transmission lines are coupled forming a hybrid metamaterial transmission line. E.g. if a qubit is placed in front of a hybrid metamaterial transmission line terminated in an open circuit, the spontaneous emission rate is weakened or unaffected depending on the transition frequency of the qubit. Some other research interests are the general analysis of metamaterial cavities and the mode structure of hybrid metamaterial cavities for QND readout of multi-qubit operators. Especially the precise answer to the question about the definition of the mode volume of a metamaterial cavity is one of our primary goals.

  2. Numerical analysis of Swiss roll metamaterials

    International Nuclear Information System (INIS)

    Demetriadou, A; Pendry, J B

    2009-01-01

    A Swiss roll metamaterial is a resonant magnetic medium, with a negative magnetic permeability for a range of frequencies, due to its self-inductance and self-capacitance components. In this paper, we discuss the band structure, S-parameters and effective electromagnetic parameters of Swiss roll metamaterials, with both analytical and numerical results, which show an exceptional convergence.

  3. Anomalous acoustic dispersion in architected microlattice metamaterials

    Science.gov (United States)

    KröDel, Sebastian; Palermo, Antonio; Daraio, Chiara

    The ability to control dispersion in acoustic metamaterials is crucial to realize acoustic filtering and rectification devices as well as perfect imaging using negative refractive index materials. Architected microlattice metamaterials immersed in fluid constitute a versatile platform for achieving such control. We investigate architected microlattice materials able to exploit locally resonant modes of their fundamental building blocks that couple with propagating acoustic waves. Using analytical, numerical and experimental methods we find that such lattice materials show a hybrid dispersion behavior governed by Biot's theory for long wavelengths and multiple scattering theory when wave frequency is close to the resonances of the building block. We identify the relevant geometric parameters to alter and control the group and phase velocities in this class of acoustic metamaterials. Furthermore, we fabricate small-scale acoustic metamaterial samples using high precision SLA additive manufacturing and test the resulting materials experimentally using a customized ultrasonic setup. This work paves the way for new acoustic devices based on microlattice metamaterials.

  4. 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....... The gain in the matrix is modeled by adding a negative imaginary part to the dielectric function of the semiconductor. It is found that the optical coefficients of the metamaterial depend on the gain magnitude in a non-trivial way: they can both increase and decrease with gain depending on the lattice...... constant of the metamaterial. This peculiar behavior is explained by the field redistribution between the lossy metal nanowires and the amplifying matrix material. These findings are significant for a proper design of nanowire metamaterials with low optical losses for diverse applications....

  5. Time-varying metamaterials based on graphene-wrapped microwires: Modeling and potential applications

    Science.gov (United States)

    Salary, Mohammad Mahdi; Jafar-Zanjani, Samad; Mosallaei, Hossein

    2018-03-01

    The successful realization of metamaterials and metasurfaces requires the judicious choice of constituent elements. In this paper, we demonstrate the implementation of time-varying metamaterials in the terahertz frequency regime by utilizing graphene-wrapped microwires as building blocks and modulation of graphene conductivity through exterior electrical gating. These elements enable enhancement of light-graphene interaction by utilizing optical resonances associated with Mie scattering, yielding a large tunability and modulation depth. We develop a semianalytical framework based on transition-matrix formulation for modeling and analysis of periodic and aperiodic arrays of such time-varying building blocks. The proposed method is validated against full-wave numerical results obtained using the finite-difference time-domain method. It provides an ideal tool for mathematical synthesis and analysis of space-time gradient metamaterials, eliminating the need for computationally expensive numerical models. Moreover, it allows for a wider exploration of exotic space-time scattering phenomena in time-modulated metamaterials. We apply the method to explore the role of modulation parameters in the generation of frequency harmonics and their emerging wavefronts. Several potential applications of such platforms are demonstrated, including frequency conversion, holographic generation of frequency harmonics, and spatiotemporal manipulation of light. The presented results provide key physical insights to design time-modulated functional metadevices using various building blocks and open up new directions in the emerging paradigm of time-modulated metamaterials.

  6. Experimental demonstration of ultrasensitive sensing with terahertz metamaterial absorbers: A comparison with the metasurfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cong, Longqing; Singh, Ranjan, E-mail: ranjans@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Tan, Siyu [School of Electrical Engineering and Computer Science, Oklahoma State University, Stillwater, Oklahoma 87074 (United States); Key Lab of All Optical Network and Advanced Telecommunication Network of EMC, Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044 (China); Yahiaoui, Riad [XLIM, Limoges University, CNRS, UMR 7252, 7 rue Jules Vallès, F-19100 Brive (France); Yan, Fengping [Key Lab of All Optical Network and Advanced Telecommunication Network of EMC, Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Weili [School of Electrical Engineering and Computer Science, Oklahoma State University, Stillwater, Oklahoma 87074 (United States)

    2015-01-19

    Planar metasurfaces and plasmonic resonators have shown great promise for sensing applications across the electromagnetic domain ranging from the microwaves to the optical frequencies. However, these sensors suffer from lower figure of merit and sensitivity due to the radiative and the non-radiative loss channels in the plasmonic metamaterial systems. We demonstrate a metamaterial absorber based ultrasensitive sensing scheme at the terahertz frequencies with significantly enhanced sensitivity and an order of magnitude higher figure of merit compared to planar metasurfaces. Magnetic and electric resonant field enhancement in the impedance matched absorber cavity enables stronger interaction with the dielectric analyte. This finding opens up opportunities for perfect metamaterial absorbers to be applied as efficient sensors in the finger print region of the electromagnetic spectrum with several organic, explosive, and bio-molecules that have unique spectral signature at the terahertz frequencies.

  7. A wave-bending structure at Ka-band using 3D-printed metamaterial

    Science.gov (United States)

    Wu, Junqiang; Liang, Min; Xin, Hao

    2018-03-01

    Three-dimensional printing technologies enable metamaterials of complex structures with arbitrary inhomogeneity. In this work, a 90° wave-bending structure at the Ka-band (26.5-40 GHz) based on 3D-printed metamaterials is designed, fabricated, and measured. The wave-bending effect is realized through a spatial distribution of varied effective dielectric constants. Based on the effective medium theory, different effective dielectric constants are accomplished by special, 3D-printable unit cells, which allow different ratios of dielectric to air at the unit cell level. In contrast to traditional, metallic-structure-included metamaterial designs, the reported wave-bending structure here is all dielectric and implemented by the polymer-jetting technique, which features rapid, low-cost, and convenient prototyping. Both simulation and experiment results demonstrate the effectiveness of the wave-bending structure.

  8. Lossless Authentication Watermarking Based on Adaptive Modular Arithmetic

    Directory of Open Access Journals (Sweden)

    H. Yang

    2010-04-01

    Full Text Available Reversible watermarking schemes based on modulo-256 addition may cause annoying salt-and-pepper noise. To avoid the salt-and-pepper noise, a reversible watermarking scheme using human visual perception characteristics and adaptive modular arithmetic is proposed. First, a high-bit residual image is obtained by extracting the most significant bits (MSB of the original image, and a new spatial visual perception model is built according to the high-bit residual image features. Second, the watermark strength and the adaptive divisor of modulo operation for each pixel are determined by the visual perception model. Finally, the watermark is embedded into different least significant bits (LSB of original image with adaptive modulo addition. The original image can be losslessly recovered if the stego-image has not been altered. Extensive experiments show that the proposed algorithm eliminates the salt-and-pepper noise effectively, and the visual quality of the stego-image with the proposed algorithm has been dramatically improved over some existing reversible watermarking algorithms. Especially, the stegoimage of this algorithm has about 9.9864 dB higher PSNR value than that of modulo-256 addition based reversible watermarking scheme.

  9. Architecture for dynamically reconfigurable real-time lossless compression

    Science.gov (United States)

    Carter, Alison J.; Audsley, Neil C.

    2004-05-01

    Image compression is a computationally intensive task, which can be undertaken most efficiently by dedicated hardware. If a portable device is to carry out real-time compression on a variety of image types, then it may be useful to reconfigure the circuitry dynamically. Using commercial off-the shelf (COTS) chips, reconfiguration is usually implemented by a complete re-load from memory, but it is also possible to perform a partial reconfiguration. This work studies the use of programmable hardware devices to implement the lossless JPEG compression algorithm in real-time on a stream of independent image frames. The data rate is faster than can be compressed serially in hardware by a single processor, so the operation is split amongst several processors. These are implemented as programmable circuits, together with necessary buffering of input and output data. The timing of input and output, bearing in mind the different, and context-dependent amounts of data due to Huffman coding, is analyzed using storage-timing graphs. Because there may be differing parameters from one frame to the next, several different configurations are prepared and stored, ready to load as required. The scheduling of these reconfigurations, and the distribution/recombination of data streams is studied, giving an analysis of the real-time performance.

  10. Auxetic mechanical metamaterials

    NARCIS (Netherlands)

    Kolken, H. M A; Zadpoor, A.A.

    2017-01-01

    The surge of interest in so-called "designer materials" during the last few years together with recent advances in additive manufacturing (3D printing) techniques that enable fabrication of materials with arbitrarily complex nano/micro-architecture have attracted increasing attention to the

  11. Watermark Compression in Medical Image Watermarking Using Lempel-Ziv-Welch (LZW) Lossless Compression Technique.

    Science.gov (United States)

    Badshah, Gran; Liew, Siau-Chuin; Zain, Jasni Mohd; Ali, Mushtaq

    2016-04-01

    In teleradiology, image contents may be altered due to noisy communication channels and hacker manipulation. Medical image data is very sensitive and can not tolerate any illegal change. Illegally changed image-based analysis could result in wrong medical decision. Digital watermarking technique can be used to authenticate images and detect as well as recover illegal changes made to teleradiology images. Watermarking of medical images with heavy payload watermarks causes image perceptual degradation. The image perceptual degradation directly affects medical diagnosis. To maintain the image perceptual and diagnostic qualities standard during watermarking, the watermark should be lossless compressed. This paper focuses on watermarking of ultrasound medical images with Lempel-Ziv-Welch (LZW) lossless-compressed watermarks. The watermark lossless compression reduces watermark payload without data loss. In this research work, watermark is the combination of defined region of interest (ROI) and image watermarking secret key. The performance of the LZW compression technique was compared with other conventional compression methods based on compression ratio. LZW was found better and used for watermark lossless compression in ultrasound medical images watermarking. Tabulated results show the watermark bits reduction, image watermarking with effective tamper detection and lossless recovery.

  12. Dielectric Metamaterial Reflector

    Science.gov (United States)

    2017-02-14

    evaporation rates. The design also includes a glass window to enable monitoring of the film growth process. The cell design will allow films to be...we consider a thin SiO2 coating on the InP spheres, as shown in Fig. 1(a), to allow for tuning of the periodicity of the close-packed structure...packed high-index InP spheres with SiO2 coatings. The structure consists of three layers of 360 nm indium-phosphide spheres with 60-nm-thick SiO2

  13. Lossless compression of multispectral images using spectral information

    Science.gov (United States)

    Ma, Long; Shi, Zelin; Tang, Xusheng

    2009-10-01

    Multispectral images are available for different purposes due to developments in spectral imaging systems. The sizes of multispectral images are enormous. Thus transmission and storage of these volumes of data require huge time and memory resources. That is why compression algorithms must be developed. A salient property of multispectral images is that strong spectral correlation exists throughout almost all bands. This fact is successfully used to predict each band based on the previous bands. We propose to use spectral linear prediction and entropy coding with context modeling for encoding multispectral images. Linear prediction predicts the value for the next sample and computes the difference between predicted value and the original value. This difference is usually small, so it can be encoded with less its than the original value. The technique implies prediction of each image band by involving number of bands along the image spectra. Each pixel is predicted using information provided by pixels in the previous bands in the same spatial position. As done in the JPEG-LS, the proposed coder also represents the mapped residuals by using an adaptive Golomb-Rice code with context modeling. This residual coding is context adaptive, where the context used for the current sample is identified by a context quantization function of the three gradients. Then, context-dependent Golomb-Rice code and bias parameters are estimated sample by sample. The proposed scheme was compared with three algorithms applied to the lossless compression of multispectral images, namely JPEG-LS, Rice coding, and JPEG2000. Simulation tests performed on AVIRIS images have demonstrated that the proposed compression scheme is suitable for multispectral images.

  14. 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.

  15. 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.

  16. Magneto-optical response in bimetallic metamaterials

    Science.gov (United States)

    Atmatzakis, Evangelos; Papasimakis, Nikitas; Fedotov, Vassili; Vienne, Guillaume; Zheludev, Nikolay I.

    2018-01-01

    We demonstrate resonant Faraday polarization rotation in plasmonic arrays of bimetallic nano-ring resonators consisting of Au and Ni sections. This metamaterial design allows the optimization of the trade-off between the enhancement of magneto-optical effects and plasmonic dissipation. Nickel sections corresponding to as little as 6% of the total surface of the metamaterial result in magneto-optically induced polarization rotation equal to that of a continuous nickel film. Such bimetallic metamaterials can be used in compact magnetic sensors, active plasmonic components, and integrated photonic circuits.

  17. Graphene-enhanced metamaterials in THz applications

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Chigrin, Dmitry N.; Khromova, Irina

    Terahertz (THz) radiation is widely employed in a broad range of fields in biology, medicine, communication, security, chemistry, and spectroscopy. To expand the application of terahertz radiation new device designs and fabrication methods are needed. The ability of metamaterials to manipulate...... 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...... on hyperbolic-like dispersion [4]. We believe that graphene-enhanced metamaterials constitute a useful functional element for the THz-infrared integrated optics devices....

  18. Design and optimization of membrane-type acoustic metamaterials

    Science.gov (United States)

    Blevins, Matthew Grant

    One of the most common problems in noise control is the attenuation of low frequency noise. Typical solutions require barriers with high density and/or thickness. Membrane-type acoustic metamaterials are a novel type of engineered material capable of high low-frequency transmission loss despite their small thickness and light weight. These materials are ideally suited to applications with strict size and weight limitations such as aircraft, automobiles, and buildings. The transmission loss profile can be manipulated by changing the micro-level substructure, stacking multiple unit cells, or by creating multi-celled arrays. To date, analysis has focused primarily on experimental studies in plane-wave tubes and numerical modeling using finite element methods. These methods are inefficient when used for applications that require iterative changes to the structure of the material. To facilitate design and optimization of membrane-type acoustic metamaterials, computationally efficient dynamic models based on the impedance-mobility approach are proposed. Models of a single unit cell in a waveguide and in a baffle, a double layer of unit cells in a waveguide, and an array of unit cells in a baffle are studied. The accuracy of the models and the validity of assumptions used are verified using a finite element method. The remarkable computational efficiency of the impedance-mobility models compared to finite element methods enables implementation in design tools based on a graphical user interface and in optimization schemes. Genetic algorithms are used to optimize the unit cell design for a variety of noise reduction goals, including maximizing transmission loss for broadband, narrow-band, and tonal noise sources. The tools for design and optimization created in this work will enable rapid implementation of membrane-type acoustic metamaterials to solve real-world noise control problems.

  19. Controlling the emission and propagation of light with nano-plasmonic metamaterials and metasurfaces

    Science.gov (United States)

    Ni, Xingjie

    Metamaterials---artificially structured materials with engineered electromagnetic properties---have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities. Metasurfaces are subwavelength thin metamaterial layers to introduce unusual properties do not exist in nature. They can play a fundamental role in generating synthetic scattering diagrams of macroscopic objects. Optical metamaterials and metasurfaces have enabled unprecedented flexibility in manipulating light waves and producing new functionalities. We have studied various topics in this field, from designs to potential applications. We experimentally demonstrated the world's first optical metasurface which is capable of precisely manipulating light in arbitrary ways over a broad range of near-infrared light, which could make possible of many optical innovations such as more powerful microscopes, telecommunications and computers. We proposed the first hyperbolic metasurface, which consist of a highly anisotropic material layer and an isotropic material layer can support Dyakonov surface waves that have hyperbolic dispersion. This type of metasurfaces support a broadband singularity in the photonic density of states, which opens up another possibility to engineer the spontaneous emission efficiency. We also developed a set of parallel simulation tools which can handle a variety of problems in nanophotonics and plasmonics. Especially, we established an on-line research environment for the research community with six tools, which deliver a cloud computing service with no demand for either any powerful computational hardware or any additional software installations and cover a range of tasks including the design and simulation of complex transformation optics devices and optical metamaterials.

  20. Directed-Assembly of Block Copolymers for Large-Scale, Three-Dimensional, Optical Metamaterials at Visible Wavelengths. Final LDRD Report

    Energy Technology Data Exchange (ETDEWEB)

    Hiszpanski, Anna M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-10-26

    Metamaterials are composites with patterned subwavelength features where the choice of materials and subwavelength structuring bestows upon the metamaterials unique optical properties not found in nature, thereby enabling optical applications previously considered impossible. However, because the structure of optical metamaterials must be subwavelength, metamaterials operating at visible wavelengths require features on the order of 100 nm or smaller, and such resolution typically requires top-down lithographic fabrication techniques that are not easily scaled to device-relevant areas that are square centimeters in size. In this project, we developed a new fabrication route using block copolymers to make over large device-relevant areas optical metamaterials that operate at visible wavelengths. Our structures are smaller in size (sub-100 nm) and cover a larger area (cm2) than what has been achieved with traditional nanofabrication routes. To guide our experimental efforts, we developed an algorithm to calculate the expected optical properties (specifically the index of refraction) of such metamaterials that predicts that we can achieve surprisingly large changes in optical properties with small changes in metamaterials’ structure. In the course of our work, we also found that the ordered metal nanowires meshes produced by our scalable fabrication route for making optical metamaterials may also possibly act as transparent electrodes, which are needed in electrical displays and solar cells. We explored the ordered metal nanowires meshes’ utility for this application and developed design guidelines to aide our experimental efforts.

  1. 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....

  2. Broadband plasmon induced transparency in terahertz metamaterials

    KAUST Repository

    Zhu, Zhihua; Yang, Xu; Gu, Jianqiang; Jiang, Jun; Yue, Weisheng; Tian, Zhen; Tonouchi, Masayoshi; Han, Jiaguang; Zhang, Weili

    2013-01-01

    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

  3. Topological sound in active-liquid metamaterials

    Science.gov (United States)

    Souslov, Anton; van Zuiden, Benjamin C.; Bartolo, Denis; Vitelli, Vincenzo

    2017-11-01

    Liquids composed of self-propelled particles have been experimentally realized using molecular, colloidal or macroscopic constituents. These active liquids can flow spontaneously even in the absence of an external drive. Unlike spontaneous active flow, the propagation of density waves in confined active liquids is not well explored. Here, we exploit a mapping between density waves on top of a chiral flow and electrons in a synthetic gauge field to lay out design principles for artificial structures termed topological active metamaterials. We design metamaterials that break time-reversal symmetry using lattices composed of annular channels filled with a spontaneously flowing active liquid. Such active metamaterials support topologically protected sound modes that propagate unidirectionally, without backscattering, along either sample edges or domain walls and despite overdamped particle dynamics. Our work illustrates how parity-symmetry breaking in metamaterial structure combined with microscopic irreversibility of active matter leads to novel functionalities that cannot be achieved using only passive materials.

  4. 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...

  5. Interferometric direction finding with a metamaterial detector

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, Suresh; Schurig, David, E-mail: david.schurig@utah.edu [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Shrekenhamer, David; Padilla, Willie [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Xu, Wangren; Sonkusale, Sameer [Department of Electrical and Computer Engineering, Tufts University, Medford, Massachusetts 02155 (United States)

    2013-12-16

    We present measurements and analysis demonstrating useful direction finding of sources in the S band (2–4 GHz) using a metamaterial detector. An augmented metamaterial absorber that supports magnitude and phase measurement of the incident electric field, within each unit cell, is described. The metamaterial is implemented in a commercial printed circuit board process with off-board back-end electronics. We also discuss on-board back-end implementation strategies. Direction finding performance is analyzed for the fabricated metamaterial detector using simulated data and the standard algorithm, MUtiple SIgnal Classification. The performance of this complete system is characterized by its angular resolution as a function of radiation density at the detector. Sources with power outputs typical of mobile communication devices can be resolved at kilometer distances with sub-degree resolution and high frame rates.

  6. Metamaterial polarization converter analysis: limits of performance

    DEFF Research Database (Denmark)

    Markovich, Dmitry L.; Andryieuski, Andrei; Zalkovskij, Maksim

    2013-01-01

    and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design......In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed...... level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter...

  7. Quantum levitation by left-handed metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Leonhardt, Ulf; Philbin, Thomas G [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom)

    2007-08-15

    Left-handed metamaterials make perfect lenses that image classical electromagnetic fields with significantly higher resolution than the diffraction limit. Here, we consider the quantum physics of such devices. We show that the Casimir force of two conducting plates may turn from attraction to repulsion if a perfect lens is sandwiched between them. For optical left-handed metamaterials, this repulsive force of the quantum vacuum may levitate ultra-thin mirrors.

  8. Quantum levitation by left-handed metamaterials

    International Nuclear Information System (INIS)

    Leonhardt, Ulf; Philbin, Thomas G

    2007-01-01

    Left-handed metamaterials make perfect lenses that image classical electromagnetic fields with significantly higher resolution than the diffraction limit. Here, we consider the quantum physics of such devices. We show that the Casimir force of two conducting plates may turn from attraction to repulsion if a perfect lens is sandwiched between them. For optical left-handed metamaterials, this repulsive force of the quantum vacuum may levitate ultra-thin mirrors

  9. Dynamic metamaterial aperture for microwave imaging

    International Nuclear Information System (INIS)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R.

    2015-01-01

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture

  10. Dynamic metamaterial aperture for microwave imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R. [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, 27708 (United States)

    2015-11-16

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  11. 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.

  12. Lossless quantum data compression and secure direct communication

    Science.gov (United States)

    Boström, Kim

    2004-07-01

    This thesis deals with the encoding and transmission of information through a quantum channel. A quantum channel is a quantum mechanical system whose state is manipulated by a sender and read out by a receiver. The individual state of the channel represents the message. The two topics of the thesis comprise 1) the possibility of compressing a message stored in a quantum channel without loss of information and 2) the possibility to communicate a message directly from one party to another in a secure manner, that is, a third party is not able to eavesdrop the message without being detected. The main results of the thesis are the following. A general framework for variable-length quantum codes is worked out. These codes are necessary to make lossless compression possible. Due to the quantum nature of the channel, the encoded messages are in general in a superposition of different lengths. It is found to be impossible to compress a quantum message without loss of information if the message is not apriori known to the sender. In the other case it is shown that lossless quantum data compression is possible and a lower bound on the compression rate is derived. Furthermore, an explicit compression scheme is constructed that works for arbitrarily given source message ensembles. A quantum cryptographic protocol - the “ping-pong protocol” - is presented that realizes the secure direct communication of classical messages through a quantum channel. The security of the protocol against arbitrary eavesdropping attacks is proven for the case of an ideal quantum channel. In contrast to other quantum cryptographic protocols, the ping-pong protocol is deterministic and can thus be used to transmit a random key as well as a composed message. The protocol is perfectly secure for the transmission of a key, and it is quasi-secure for the direct transmission of a message. The latter means that the probability of successful eavesdropping exponentially decreases with the length of the

  13. 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....

  14. Lossless Data Embedding—New Paradigm in Digital Watermarking

    Directory of Open Access Journals (Sweden)

    Jessica Fridrich

    2002-02-01

    Full Text Available One common drawback of virtually all current data embedding methods is the fact that the original image is inevitably distorted due to data embedding itself. This distortion typically cannot be removed completely due to quantization, bit-replacement, or truncation at the grayscales 0 and 255. Although the distortion is often quite small and perceptual models are used to minimize its visibility, the distortion may not be acceptable for medical imagery (for legal reasons or for military images inspected under nonstandard viewing conditions (after enhancement or extreme zoom. In this paper, we introduce a new paradigm for data embedding in images (lossless data embedding that has the property that the distortion due to embedding can be completely removed from the watermarked image after the embedded data has been extracted. We present lossless embedding methods for the uncompressed formats (BMP, TIFF and for the JPEG format. We also show how the concept of lossless data embedding can be used as a powerful tool to achieve a variety of nontrivial tasks, including lossless authentication using fragile watermarks, steganalysis of LSB embedding, and distortion-free robust watermarking.

  15. Hardware Implementation of Lossless Adaptive and Scalable Hyperspectral Data Compression for Space

    Science.gov (United States)

    Aranki, Nazeeh; Keymeulen, Didier; Bakhshi, Alireza; Klimesh, Matthew

    2009-01-01

    On-board lossless hyperspectral data compression reduces data volume in order to meet NASA and DoD limited downlink capabilities. The technique also improves signature extraction, object recognition and feature classification capabilities by providing exact reconstructed data on constrained downlink resources. At JPL a novel, adaptive and predictive technique for lossless compression of hyperspectral data was recently developed. This technique uses an adaptive filtering method and achieves a combination of low complexity and compression effectiveness that far exceeds state-of-the-art techniques currently in use. The JPL-developed 'Fast Lossless' algorithm requires no training data or other specific information about the nature of the spectral bands for a fixed instrument dynamic range. It is of low computational complexity and thus well-suited for implementation in hardware. A modified form of the algorithm that is better suited for data from pushbroom instruments is generally appropriate for flight implementation. A scalable field programmable gate array (FPGA) hardware implementation was developed. The FPGA implementation achieves a throughput performance of 58 Msamples/sec, which can be increased to over 100 Msamples/sec in a parallel implementation that uses twice the hardware resources This paper describes the hardware implementation of the 'Modified Fast Lossless' compression algorithm on an FPGA. The FPGA implementation targets the current state-of-the-art FPGAs (Xilinx Virtex IV and V families) and compresses one sample every clock cycle to provide a fast and practical real-time solution for space applications.

  16. Granular metamaterials for vibration mitigation

    Science.gov (United States)

    Gantzounis, G.; Serra-Garcia, M.; Homma, K.; Mendoza, J. M.; Daraio, C.

    2013-09-01

    Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.

  17. 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...

  18. Intrinsic rippling enhances static non-reciprocity in a graphene metamaterial.

    Science.gov (United States)

    Ho, Duc Tam; Park, Harold S; Kim, Sung Youb

    2018-01-18

    In mechanical systems, Maxwell-Betti reciprocity means that the displacement at point B in response to a force at point A is the same as the displacement at point A in response to the same force applied at point B. Because the notion of reciprocity is general, fundamental, and is operant for other physical systems like electromagnetics, acoustics, and optics, there is significant interest in understanding systems that are not reciprocal, or exhibit non-reciprocity. However, most studies on non-reciprocity have occurred in bulk-scale structures for dynamic problems involving time reversal symmetry. As a result, little is known about the mechanisms governing static non-reciprocal responses, particularly in atomically-thin two-dimensional materials like graphene. Here, we use classical atomistic simulations to demonstrate that out-of-plane ripples, which are intrinsic to graphene, enable significant, multiple orders of magnitude enhancements in the statically non-reciprocal response of graphene metamaterials. Specifically, we find that a striking interplay between the ripples and the stress fields that are induced in the metamaterials due to their geometry impacts the displacements that are transmitted by the metamaterial, thus leading to a significantly enhanced static non-reciprocal response. This study thus demonstrates the potential of two-dimensional mechanical metamaterials for symmetry-breaking applications.

  19. Ultra-High Resolution Ion Mobility Separations Utilizing Traveling Waves in a 13 m Serpentine Path Length Structures for Lossless Ion Manipulations Module

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Liulin; Ibrahim, Yehia M.; Hamid, Ahmed M.; Garimella, Sandilya V. B.; Webb, Ian K.; Zheng, Xueyun; Prost, Spencer A.; Sandoval, Jeremy A.; Norheim, Randolph V.; Anderson, Gordon A.; Tolmachev, Aleksey V.; Baker, Erin S.; Smith, Richard D.

    2016-09-20

    We report the development and initial evaluation of a 13-m path length Structures for Lossless Manipulations (SLIM) module for achieving high resolution separations using traveling waves (TW) with ion mobility (IM) spectrometry. The TW SLIM module was fabricated using two mirror-image printed circuit boards with appropriately configured RF, DC and TW electrodes and positioned with a 2.75-mm inter-surface gap. Ions were effective confined between the surfaces by RF-generated pseudopotential fields and moved losslessly through a serpentine path including 44 “U” turns using TWs. The ion mobility resolution was characterized at different pressures, gaps between the SLIM surfaces, TW and RF parameters. After initial optimization the SLIM IM-MS module provided about 5-fold higher resolution separations than present commercially available drift tube or traveling wave IM-MS platforms. Peak capacity and peak generation rates achieved were 246 and 370 s-1, respectively, at a TW speed of 148 m/s. The high resolution achieved in the TW SLIM IM-MS enabled e.g., isomeric sugars (Lacto-N-fucopentaose I and Lacto-N-fucopentaose II) to be baseline resolved, and peptides from a albumin tryptic digest much better resolved than with existing commercial IM-MS platforms. The present work also provides a foundation for the development of much higher resolution SLIM devices based upon both considerably longer path lengths and multi-pass designs.

  20. 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)

  1. Highly-dispersive electromagnetic induced transparency in planar symmetric metamaterials.

    Science.gov (United States)

    Lu, Xiqun; Shi, Jinhui; Liu, Ran; Guan, Chunying

    2012-07-30

    We propose, design and experimentally demonstrate highly-dispersive electromagnetically induced transparency (EIT) in planar symmetric metamaterials actively switched and controlled by angles of incidence. Full-wave simulation and measurement results show EIT phenomena, trapped-mode excitations and the associated local field enhancement of two symmetric metamaterials consisting of symmetrically split rings (SSR) and a fishscale (FS) metamaterial pattern, respectively, strongly depend on angles of incidence. The FS metamaterial shows much broader spectral splitting than the SSR metamaterial due to the surface current distribution variation.

  2. Programmable Self-Locking Origami Mechanical Metamaterials.

    Science.gov (United States)

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

    2018-04-01

    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.

  3. 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.

  4. Acoustic metamaterials: From local resonances to broad horizons

    Science.gov (United States)

    Ma, Guancong; Sheng, Ping

    2016-01-01

    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. PMID:26933692

  5. 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.

  6. Spider web-structured labyrinthine acoustic metamaterials for low-frequency sound control

    Science.gov (United States)

    Krushynska, A. O.; Bosia, F.; Miniaci, M.; Pugno, N. M.

    2017-10-01

    Attenuating low-frequency sound remains a challenge, despite many advances in this field. Recently-developed acoustic metamaterials are characterized by unusual wave manipulation abilities that make them ideal candidates for efficient subwavelength sound control. In particular, labyrinthine acoustic metamaterials exhibit extremely high wave reflectivity, conical dispersion, and multiple artificial resonant modes originating from the specifically-designed topological architectures. These features enable broadband sound attenuation, negative refraction, acoustic cloaking and other peculiar effects. However, hybrid and/or tunable metamaterial performance implying enhanced wave reflection and simultaneous presence of conical dispersion at desired frequencies has not been reported so far. In this paper, we propose a new type of labyrinthine acoustic metamaterials (LAMMs) with hybrid dispersion characteristics by exploiting spider web-structured configurations. The developed design approach consists in adding a square surrounding frame to sectorial circular-shaped labyrinthine channels described in previous publications (e.g. (11)). Despite its simplicity, this approach provides tunability in the metamaterial functionality, such as the activation/elimination of subwavelength band gaps and negative group-velocity modes by increasing/decreasing the edge cavity dimensions. Since these cavities can be treated as extensions of variable-width internal channels, it becomes possible to exploit geometrical features, such as channel width, to shift the band gap position and size to desired frequencies. Time transient simulations demonstrate the effectiveness of the proposed metastructures for wave manipulation in terms of transmission or reflection coefficients, amplitude attenuation and time delay at subwavelength frequencies. The obtained results can be important for practical applications of LAMMs such as lightweight acoustic barriers with enhanced broadband wave

  7. Spider web-structured labyrinthine acoustic metamaterials for low-frequency sound control

    International Nuclear Information System (INIS)

    Krushynska, A O; Bosia, F; Miniaci, M; Pugno, N M

    2017-01-01

    Attenuating low-frequency sound remains a challenge, despite many advances in this field. Recently-developed acoustic metamaterials are characterized by unusual wave manipulation abilities that make them ideal candidates for efficient subwavelength sound control. In particular, labyrinthine acoustic metamaterials exhibit extremely high wave reflectivity, conical dispersion, and multiple artificial resonant modes originating from the specifically-designed topological architectures. These features enable broadband sound attenuation, negative refraction, acoustic cloaking and other peculiar effects. However, hybrid and/or tunable metamaterial performance implying enhanced wave reflection and simultaneous presence of conical dispersion at desired frequencies has not been reported so far. In this paper, we propose a new type of labyrinthine acoustic metamaterials (LAMMs) with hybrid dispersion characteristics by exploiting spider web-structured configurations. The developed design approach consists in adding a square surrounding frame to sectorial circular-shaped labyrinthine channels described in previous publications (e.g. (11)). Despite its simplicity, this approach provides tunability in the metamaterial functionality, such as the activation/elimination of subwavelength band gaps and negative group-velocity modes by increasing/decreasing the edge cavity dimensions. Since these cavities can be treated as extensions of variable-width internal channels, it becomes possible to exploit geometrical features, such as channel width, to shift the band gap position and size to desired frequencies. Time transient simulations demonstrate the effectiveness of the proposed metastructures for wave manipulation in terms of transmission or reflection coefficients, amplitude attenuation and time delay at subwavelength frequencies. The obtained results can be important for practical applications of LAMMs such as lightweight acoustic barriers with enhanced broadband wave

  8. 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.

  9. 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.

  10. Hyperbolic metamaterial lens with hydrodynamic nonlocal response.

    Science.gov (United States)

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

    2013-06-17

    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 free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion curves numerically. As an application, we find that the focusing characteristics of a HMM lens 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.

  11. Broadband plasmon induced transparency in terahertz metamaterials

    International Nuclear Information System (INIS)

    Zhu Zhihua; Yang Xu; Gu Jianqiang; Jiang Jun; Tian Zhen; Han Jiaguang; Zhang Weili; Yue Weisheng; Tonouchi, Masayoshi

    2013-01-01

    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. (paper)

  12. Highly dispersive transparency in coupled metamaterials

    International Nuclear Information System (INIS)

    Thuy, V T T; Park, J W; Lee, Y P; Tung, N T; Lam, V D; Rhee, J Y

    2010-01-01

    We investigate the coupling between bright and quasi-dark eigenmodes in a planar metamaterial supporting highly dispersive transparency. The specific design of such a metamaterial consists of a cut wire (CW) and a single-gap split-ring resonator (SRR). Through the numerical simulation and the equivalent-circuit analysis, we demonstrate that the response of the SRR, which is weakly excited by external electric field, plays the role of a quasi-dark eigenmode in the presence of a strongly radiative CW. Furthermore, by extending and relating our study to the trapped mode resonances and the coupling between dark and bright modes, a more comprehensive perspective for the metamaterial realization of highly dispersive transmission and slow-light applications is provided

  13. Hardware Implementation of Lossless Adaptive Compression of Data From a Hyperspectral Imager

    Science.gov (United States)

    Keymeulen, Didlier; Aranki, Nazeeh I.; Klimesh, Matthew A.; Bakhshi, Alireza

    2012-01-01

    Efficient onboard data compression can reduce the data volume from hyperspectral imagers on NASA and DoD spacecraft in order to return as much imagery as possible through constrained downlink channels. Lossless compression is important for signature extraction, object recognition, and feature classification capabilities. To provide onboard data compression, a hardware implementation of a lossless hyperspectral compression algorithm was developed using a field programmable gate array (FPGA). The underlying algorithm is the Fast Lossless (FL) compression algorithm reported in Fast Lossless Compression of Multispectral- Image Data (NPO-42517), NASA Tech Briefs, Vol. 30, No. 8 (August 2006), p. 26 with the modification reported in Lossless, Multi-Spectral Data Comressor for Improved Compression for Pushbroom-Type Instruments (NPO-45473), NASA Tech Briefs, Vol. 32, No. 7 (July 2008) p. 63, which provides improved compression performance for data from pushbroom-type imagers. An FPGA implementation of the unmodified FL algorithm was previously developed and reported in Fast and Adaptive Lossless Onboard Hyperspectral Data Compression System (NPO-46867), NASA Tech Briefs, Vol. 36, No. 5 (May 2012) p. 42. The essence of the FL algorithm is adaptive linear predictive compression using the sign algorithm for filter adaption. The FL compressor achieves a combination of low complexity and compression effectiveness that exceeds that of stateof- the-art techniques currently in use. The modification changes the predictor structure to tolerate differences in sensitivity of different detector elements, as occurs in pushbroom-type imagers, which are suitable for spacecraft use. The FPGA implementation offers a low-cost, flexible solution compared to traditional ASIC (application specific integrated circuit) and can be integrated as an intellectual property (IP) for part of, e.g., a design that manages the instrument interface. The FPGA implementation was benchmarked on the Xilinx

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Magnetic nanoparticles for tunable microwave metamaterials

    KAUST Repository

    Noginova, Natalia; Williams, Quincy Leon; Dallas, Panagiotis; Giannelis, Emmanuel P.

    2012-01-01

    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.

  19. 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....

  20. Trampoline metamaterial: Local resonance enhancement by springboards

    Science.gov (United States)

    Bilal, Osama R.; Hussein, Mahmoud I.

    2013-09-01

    We investigate the dispersion characteristics of locally resonant elastic metamaterials formed by the erection of pillars on the solid regions in a plate patterned by a periodic array of holes. We show that these solid regions effectively act as springboards leading to an enhanced resonance behavior by the pillars when compared to the nominal case of pillars with no holes. This local resonance amplification phenomenon, which we define as the trampoline effect, is shown to cause subwavelength bandgaps to increase in size by up to a factor of 4. This outcome facilitates the utilization of subwavelength metamaterial properties over exceedingly broad frequency ranges.

  1. 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.

  2. Hyperbolic metamaterials: Nonlocal response regularizes broadband supersingularity

    DEFF Research Database (Denmark)

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

    2012-01-01

    We study metamaterials known as hyperbolic media that in the usual local-response approximation exhibit hyperbolic dispersion and an associated broadband singularity in the density of states. Instead, from the more microscopic hydrodynamic Drude theory we derive qualitatively different optical...... properties of these metamaterials, due to the free-electron nonlocal optical response of their metal constituents. We demonstrate that nonlocal response gives rise to a large-wavevector cutoff in the dispersion that is inversely proportional to the Fermi velocity of the electron gas, but also for small...

  3. 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

  4. 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.

  5. Metamaterial mirrors in optoelectronic devices

    KAUST Repository

    Esfandyarpour, Majid; Garnett, Erik C.; Cui, Yi; McGehee, Michael D.; Brongersma, Mark L.

    2014-01-01

    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.

  6. Thermodynamics of superconducting quantum metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Dallaire-Demers, Pierre-Luc; Wilhelm-Mauch, Frank [Universitaet des Saarlandes (Germany)

    2015-07-01

    Left-handed matematerials are capacitively coupled layers of inductive pieces of conductors. These systems are well studied in the context of microwave metamaterials but their full quantum description or their embedding in highly correlated materials like superconductors are still an open problem. Notably, they are known to have a Van Hove singularity in the density of states at low energy and high pseudo-momentum that could effectively couple and condense Cooper pairs. The goal of this research is to analyze the thermodynamical properties of the order parameter of stacked layers of superconductors with a small repulsive Coulomb interaction. A 3D toy model of such a material is mapped to a Fermi-Hubbard lattice. The temperature dependent anomalous correlation functions are computed variationally from a self-energy functional of a small cluster where inter-cluster tunneling is treated perturbatively. The effect of the repulsive interaction on the Cooper pairs binding can then be seen from the momentum distribution of the condensation amplitude. Such a material could potentially be realized with optical lattices or nanoscaled superconductors.

  7. A Near-Lossless Image Compression Algorithm Suitable for Hardware Design in Wireless Endoscopy System

    Directory of Open Access Journals (Sweden)

    Xie Xiang

    2007-01-01

    Full Text Available In order to decrease the communication bandwidth and save the transmitting power in the wireless endoscopy capsule, this paper presents a new near-lossless image compression algorithm based on the Bayer format image suitable for hardware design. This algorithm can provide low average compression rate ( bits/pixel with high image quality (larger than dB for endoscopic images. Especially, it has low complexity hardware overhead (only two line buffers and supports real-time compressing. In addition, the algorithm can provide lossless compression for the region of interest (ROI and high-quality compression for other regions. The ROI can be selected arbitrarily by varying ROI parameters. In addition, the VLSI architecture of this compression algorithm is also given out. Its hardware design has been implemented in m CMOS process.

  8. 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.

  9. The Self-Assembly of Nanogold for Optical Metamaterials

    Science.gov (United States)

    Nidetz, Robert A.

    2011-12-01

    Optical metamaterials are an emerging field that enables manipulation of light like never before. Producing optical metamaterials requires sub-wavelength building blocks. The focus here was to develop methods to produce building blocks for metamaterials from nanogold. Electron-beam lithography was used to define an aminosilane patterned chemical template in order to electrostatically self-assemble citrate-capped gold nanoparticles. Equilibrium self-assembly was achieved in 20 minutes by immersing chemical templates into gold nanoparticle solutions. The number of nanoparticles that self-assembled on an aminosilane dot was controlled by manipulating the diameters of the dots and nanoparticles. Adding salt to the nanoparticle solution enabled the nanoparticles to self-assemble in greater numbers on the same sized dot. However, the preparation of the nanoparticle solution containing salt was sensitive to spikes in the salt concentration which led to aggregation of the nanoparticles and non-specific deposition. Gold nanorods were also electrostatically self-assembled. Polyelectrolyte-coated gold nanorods were patterned with limited success. A polyelectrolyte chemical template also patterned gold nanorods, but the gold nanorods preferred to pattern on the edges of the pattern. Ligand-exchanged gold nanorods displayed the best self-assembly, but suffered from slow kinetics. Self-assembled gold nanoparticles were cross-linked with poly(diallyldimethylammonium chloride). The poly(diallyldimethylammonium chloride) allowed additional nanoparticles to pattern on top of the already patterned nanoparticles. Cross-linked nanoparticles were lifted-off of the substrate by sonication in a sodium hydroxide solution. The presence of van der Waals forces and/or amine bonding prevent the nanogold from lifting-off without sonication. A good-solvent evaporation process was used to self-assemble poly(styrene) coated gold nanoparticles into spherical microbead assemblies. The use of larger

  10. Fast and Adaptive Lossless On-Board Hyperspectral Data Compression System for Space Applications

    Science.gov (United States)

    Aranki, Nazeeh; Bakhshi, Alireza; Keymeulen, Didier; Klimesh, Matthew

    2009-01-01

    Efficient on-board lossless hyperspectral data compression reduces the data volume necessary to meet NASA and DoD limited downlink capabilities. The techniques also improves signature extraction, object recognition and feature classification capabilities by providing exact reconstructed data on constrained downlink resources. At JPL a novel, adaptive and predictive technique for lossless compression of hyperspectral data was recently developed. This technique uses an adaptive filtering method and achieves a combination of low complexity and compression effectiveness that far exceeds state-of-the-art techniques currently in use. The JPL-developed 'Fast Lossless' algorithm requires no training data or other specific information about the nature of the spectral bands for a fixed instrument dynamic range. It is of low computational complexity and thus well-suited for implementation in hardware, which makes it practical for flight implementations of pushbroom instruments. A prototype of the compressor (and decompressor) of the algorithm is available in software, but this implementation may not meet speed and real-time requirements of some space applications. Hardware acceleration provides performance improvements of 10x-100x vs. the software implementation (about 1M samples/sec on a Pentium IV machine). This paper describes a hardware implementation of the JPL-developed 'Fast Lossless' compression algorithm on a Field Programmable Gate Array (FPGA). The FPGA implementation targets the current state of the art FPGAs (Xilinx Virtex IV and V families) and compresses one sample every clock cycle to provide a fast and practical real-time solution for Space applications.

  11. Volumetric Medical Image Coding: An Object-based, Lossy-to-lossless and Fully Scalable Approach

    Science.gov (United States)

    Danyali, Habibiollah; Mertins, Alfred

    2011-01-01

    In this article, an object-based, highly scalable, lossy-to-lossless 3D wavelet coding approach for volumetric medical image data (e.g., magnetic resonance (MR) and computed tomography (CT)) is proposed. The new method, called 3DOBHS-SPIHT, is based on the well-known set partitioning in the hierarchical trees (SPIHT) algorithm and supports both quality and resolution scalability. The 3D input data is grouped into groups of slices (GOS) and each GOS is encoded and decoded as a separate unit. The symmetric tree definition of the original 3DSPIHT is improved by introducing a new asymmetric tree structure. While preserving the compression efficiency, the new tree structure allows for a small size of each GOS, which not only reduces memory consumption during the encoding and decoding processes, but also facilitates more efficient random access to certain segments of slices. To achieve more compression efficiency, the algorithm only encodes the main object of interest in each 3D data set, which can have any arbitrary shape, and ignores the unnecessary background. The experimental results on some MR data sets show the good performance of the 3DOBHS-SPIHT algorithm for multi-resolution lossy-to-lossless coding. The compression efficiency, full scalability, and object-based features of the proposed approach, beside its lossy-to-lossless coding support, make it a very attractive candidate for volumetric medical image information archiving and transmission applications. PMID:22606653

  12. Metamaterial Receivers for High Efficiency Concentrated Solar Energy Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Yellowhair, Julius E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Kwon, Hoyeong [Univ. of Texas, Austin, TX (United States). Dept. of Electrical and Computer Engineering; Alu, Andrea [Univ. of Texas, Austin, TX (United States). Dept. of Electrical and Computer Engineering; Jarecki, Robert L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.; Shinde, Subhash L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Concentrating Solar Technologies Dept.

    2016-09-01

    Operation of concentrated solar power receivers at higher temperatures (>700°C) would enable supercritical carbon dioxide (sCO2) power cycles for improved power cycle efficiencies (>50%) and cost-effective solar thermal power. Unfortunately, radiative losses at higher temperatures in conventional receivers can negatively impact the system efficiency gains. One approach to improve receiver thermal efficiency is to utilize selective coatings that enhance absorption across the visible solar spectrum while minimizing emission in the infrared to reduce radiative losses. Existing coatings, however, tend to degrade rapidly at elevated temperatures. In this report, we report on the initial designs and fabrication of spectrally selective metamaterial-based absorbers for high-temperature, high-thermal flux environments important for solarized sCO2 power cycles. Metamaterials are structured media whose optical properties are determined by sub-wavelength structural features instead of bulk material properties, providing unique solutions by decoupling the optical absorption spectrum from thermal stability requirements. The key enabling innovative concept proposed is the use of structured surfaces with spectral responses that can be tailored to optimize the absorption and retention of solar energy for a given temperature range. In this initial study through the Academic Alliance partnership with University of Texas at Austin, we use Tungsten for its stability in expected harsh environments, compatibility with microfabrication techniques, and required optical performance. Our goal is to tailor the optical properties for high (near unity) absorptivity across the majority of the solar spectrum and over a broad range of incidence angles, and at the same time achieve negligible absorptivity in the near infrared to optimize the energy absorbed and retained. To this goal, we apply the recently developed concept of plasmonic Brewster angle to suitably designed

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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 term...

  19. 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

  20. Strain Imaging Using Terahertz Waves and Metamaterials

    Science.gov (United States)

    2016-11-01

    predictions. 14. SUBJECT TERMS Birefringence, Terahertz Waves, Metamaterials 15. NUMBER OF PAGES 16 16. PRICE CODE 17. SECURITY...opaque objects by using the principles of strain-induced birefringence. 4 III. CONCEPT To overcome the inability of visual light to penetrate ...opaque objects, terahertz radiation was investigated. Longer wavelength EM waves, such as radio waves, have excellent penetration ability but low image

  1. Optical properties of silver composite metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Orbons, S.M. [School of Physics, University of Melbourne, Victoria 3010 (Australia)]. E-mail: sorbons@ph.unimelb.edu.au; Freeman, D. [Centre for Ultrahigh-bandwidth Devices for Optical Systems, Laser Physics Centre, Australian National University, ACT 0200 (Australia); Luther-Davies, B. [Centre for Ultrahigh-bandwidth Devices for Optical Systems, Laser Physics Centre, Australian National University, ACT 0200 (Australia); Gibson, B.C. [Quantum Communications Victoria, School of Physics, University of Melbourne, Victoria 3010 (Australia); Huntington, S.T. [Quantum Communications Victoria, School of Physics, University of Melbourne, Victoria 3010 (Australia); Jamieson, D.N. [School of Physics, University of Melbourne, Victoria 3010 (Australia); Roberts, A. [School of Physics, University of Melbourne, Victoria 3010 (Australia)

    2007-05-15

    We present a computational and experimental study investigating the optical properties of nanoscale silver composite metamaterials fabricated by ion beam lithography. Both simulations and experimental results demonstrate high transmission efficiencies in the near infra-red through these devices. Implications for experimentally verifying the calculated near-field distributions of these materials are also discussed.

  2. 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...

  3. Casimir interactions for anisotropic magnetodielectric metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Da Rosa, Felipe S [Los Alamos National Laboratory; Dalvit, Diego A [Los Alamos National Laboratory; Milonni, Peter W [Los Alamos National Laboratory

    2008-01-01

    We extend our previous work on the generalization of the Casimir-Lifshitz theory to treat anisotropic magnetodielectric media, focusing on the forces between metals and magnetodielectric metamaterials and on the possibility of inferring magnetic effects by measurements of these forces.

  4. Local field in finite-size metamaterials

    DEFF Research Database (Denmark)

    Bordo, Vladimir

    2018-01-01

    The theory of the optical response of a metamaterial slab which is represented by metal nanoparticles embedded in a dielectric matrix is developed. It is demonstrated that the account of the reflections from the slab boundaries essentially modifies the local field in the slab and leads...

  5. Super Talbot effect in indefinite metamaterial.

    Science.gov (United States)

    Zhao, Wangshi; Huang, Xiaoyue; Lu, Zhaolin

    2011-08-01

    The Talbot effect (or the self-imaging effect) can be observed for a periodic object with a pitch larger than the diffraction limit of an imaging system, where the paraxial approximation is applied. In this paper, we show that the super Talbot effect can be achieved in an indefinite metamaterial even when the period is much smaller than the diffraction limit in both two-dimensional and three-dimensional numerical simulations, where the paraxial approximation is not applied. This is attributed to the evanescent waves, which carry the information about subwavelength features of the object, can be converted into propagating waves and then conveyed to far field by the metamaterial, where the permittivity in the propagation direction is negative while the transverse ones are positive. The indefinite metamaterial can be approximated by a system of thin, alternating multilayer metal and insulator (MMI) stack. As long as the loss of the metamaterial is small enough, deep subwavelength image size can be obtained in the super Talbot effect.

  6. Tunable electromagnetically induced transparency in coupled three-dimensional split-ring-resonator metamaterials

    Science.gov (United States)

    Han, Song; Cong, Longqing; Lin, Hai; Xiao, Boxun; Yang, Helin; Singh, Ranjan

    2016-01-01

    Metamaterials have recently enabled coupling induced transparency due to interference effects in coupled subwavelength resonators. In this work, we present a three dimensional (3-D) metamaterial design with six-fold rotational symmetry that shows electromagnetically induced transparency with a strong polarization dependence to the incident electromagnetic wave due to the ultra-sharp resonance line width as a result of interaction between the constituent meta-atoms. However, when the six-fold rotationally symmetric unit cell design was re-arranged into a fourfold rotational symmetry, we observed the excitation of a polarization insensitive dual-band transparency. Thus, the 3-D split-ring resonators allow new schemes to observe single and multi-band classical analogues of electromagnetically induced transparencies that has huge potential applications in slowing down light, sensing modalities, and filtering functionalities either in the passive mode or the active mode where such effects could be tuned by integrating materials with dynamic properties. PMID:26857034

  7. Efficient, Broadband and Wide-Angle Hot-Electron Transduction using Metal-Semiconductor Hyperbolic Metamaterials

    KAUST Repository

    Sakhdari, Maryam

    2016-05-20

    Hot-electron devices are emerging as promising candidates for the transduction of optical radiation into electrical current, as they enable photodetection and solar/infrared energy harvesting at sub-bandgap wavelengths. Nevertheless, poor photoconversion quantum yields and low bandwidth pose fundamental challenge to fascinating applications of hot-electron optoelectronics. Based on a novel hyperbolic metamaterial (HMM) structure, we theoretically propose a vertically-integrated hot-electron device that can efficiently couple plasmonic excitations into electron flows, with an external quantum efficiency approaching the physical limit. Further, this metamaterial-based device can have a broadband and omnidirectional response at infrared and visible wavelengths. We believe that these findings may shed some light on designing practical devices for energy-efficient photodetection and energy harvesting beyond the bandgap spectral limit.

  8. 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.

  9. 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.

  10. 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...... fabricated and characterized. The realized metamaterial fiber has been simulated to have 0.3 dB/m loss at 0.3 THz....

  11. 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.

  12. What is a good conductor for metamaterials or plasmonics

    Directory of Open Access Journals (Sweden)

    Soukoulis Costas M.

    2015-04-01

    Full Text Available We review conducting materials like metals, conducting oxides and graphene for nanophotonic applications. We emphasize that metamaterials and plasmonic systems benefit from different conducting materials. Resonant metamaterials need conductors with small resistivity, since dissipative loss in resonant metamaterials is proportional to the real part of the resistivity of the conducting medium it contains. For plasmonic systems, one must determine the propagation length at a desired level of confinement to estimate the dissipative loss.

  13. 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)

  14. Acoustic metamaterials capable of both sound insulation and energy harvesting

    Science.gov (United States)

    Li, Junfei; Zhou, Xiaoming; Huang, Guoliang; Hu, Gengkai

    2016-04-01

    Membrane-type acoustic metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications.

  15. Acoustic metamaterials capable of both sound insulation and energy harvesting

    International Nuclear Information System (INIS)

    Li, Junfei; Zhou, Xiaoming; Hu, Gengkai; Huang, Guoliang

    2016-01-01

    Membrane-type acoustic metamaterials are well known for low-frequency sound insulation. In this work, by introducing a flexible piezoelectric patch, we propose sound-insulation metamaterials with the ability of energy harvesting from sound waves. The dual functionality of the metamaterial device has been verified by experimental results, which show an over 20 dB sound transmission loss and a maximum energy conversion efficiency up to 15.3% simultaneously. This novel property makes the metamaterial device more suitable for noise control applications. (paper)

  16. Local field effects and metamaterials based on colloidal quantum dots

    International Nuclear Information System (INIS)

    Porvatkina, O V; Tishchenko, A A; Strikhanov, M N

    2015-01-01

    Metamaterials are composite structures that exhibit interesting and unusual properties, e.g. negative refractive index. In this article we consider metamaterials based on colloidal quantum dots (CQDs). We investigate these structures taking into account the local field effects and theoretically analyze expressions for permittivity and permeability of metamaterials based on CdSe CQDs. We obtain inequality describing the conditions when material with definite concentration of CQDs is metamaterial. Also we investigate how the values of dielectric polarizability and magnetic polarizability of CQDs depend on the dots radius and properties the material the quantum dots are made of. (paper)

  17. 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.

  18. 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

  19. Mechanical metamaterials at the theoretical limit of isotropic elastic stiffness

    Science.gov (United States)

    Berger, J. B.; Wadley, H. N. G.; McMeeking, R. M.

    2017-02-01

    A wide variety of high-performance applications require materials for which shape control is maintained under substantial stress, and that have minimal density. Bio-inspired hexagonal and square honeycomb structures and lattice materials based on repeating unit cells composed of webs or trusses, when made from materials of high elastic stiffness and low density, represent some of the lightest, stiffest and strongest materials available today. Recent advances in 3D printing and automated assembly have enabled such complicated material geometries to be fabricated at low (and declining) cost. These mechanical metamaterials have properties that are a function of their mesoscale geometry as well as their constituents, leading to combinations of properties that are unobtainable in solid materials; however, a material geometry that achieves the theoretical upper bounds for isotropic elasticity and strain energy storage (the Hashin-Shtrikman upper bounds) has yet to be identified. Here we evaluate the manner in which strain energy distributes under load in a representative selection of material geometries, to identify the morphological features associated with high elastic performance. Using finite-element models, supported by analytical methods, and a heuristic optimization scheme, we identify a material geometry that achieves the Hashin-Shtrikman upper bounds on isotropic elastic stiffness. Previous work has focused on truss networks and anisotropic honeycombs, neither of which can achieve this theoretical limit. We find that stiff but well distributed networks of plates are required to transfer loads efficiently between neighbouring members. The resulting low-density mechanical metamaterials have many advantageous properties: their mesoscale geometry can facilitate large crushing strains with high energy absorption, optical bandgaps and mechanically tunable acoustic bandgaps, high thermal insulation, buoyancy, and fluid storage and transport. Our relatively simple

  20. Experimental Demonstration of Anomalous Field Enhancement in All-Dielectric Transition Magnetic Metamaterials.

    Science.gov (United States)

    Sun, Jingbo; Liu, Xiaoming; Zhou, Ji; Kudyshev, Zhaxylyk; Litchinitser, Natalia M

    2015-11-04

    Anomalous field enhancement accompanied by resonant absorption phenomenon was originally discussed in the context of plasma physics and in applications related to radio-communications between the ground and spacecraft returning to Earth. Indeed, there is a critical period of time when all communications are lost due to the reflection/absorption of electromagnetic waves by the sheath of plasma created by a high speed vehicle re-entering the atmosphere. While detailed experimental studies of these phenomena in space are challenging, the emergence of electromagnetic metamaterials enables researchers exceptional flexibility to study them in the laboratory environment. Here, we experimentally demonstrated the strong localized field enhancement of magnetic field for an electromagnetic wave propagating in Mie-resonance-based inhomogeneous metamaterials with magnetic permeability gradually changing from positive to negative values. Although these experiments were performed in the microwave frequency range, the proposed all-dielectric approach to transition metamaterials can be extended to terahertz, infrared, and visible frequencies. We anticipate that these results, besides most basic science aspects, hold the potential for numerous applications, including low-intensity nonlinear transformation optics, topological photonics, and the broader area of surface and interface science.

  1. 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.

  2. 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.

  3. Manipulation of wavefront using helical metamaterials.

    Science.gov (United States)

    Yang, Zhenyu; Wang, Zhaokun; Tao, Huan; Zhao, Ming

    2016-08-08

    Helical metamaterials, a kind of 3-dimensional structure, has relatively strong coupling effect among the helical nano-wires. Therefore, it is expected to be a good candidate for generating phase shift and controlling wavefront with high efficiency. In this paper, using the finite-difference time-domain (FDTD) method, we studied the phase shift properties in the helical metamaterials. It is found that the phase shift occurs for both transmitted and reflected light waves. And the maximum of reflection coefficients can reach over 60%. In addition, the phase shift (φ) is dispersionless in the range of 600 nm to 860 nm, that is, it is only dominated by the initial angle (θ) of the helix. The relationship between them is φ = ± 2θ. Using Jones calculus we give a further explanation for these properties. Finally, by arranging the helixes in an array with a constant phase gradient, the phenomenon of anomalous refraction was also observed in a broad wavelength range.

  4. 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 free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion curves numerically. As an application, we find that the focusing characteristics of a HMM lens...... 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...

  5. Wireless energy transfer between anisotropic metamaterials shells

    International Nuclear Information System (INIS)

    Díaz-Rubio, Ana; Carbonell, Jorge; Sánchez-Dehesa, José

    2014-01-01

    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

  6. 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.

  7. 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)

  8. 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....

  9. Nonlinearities in Periodic Structures and Metamaterials

    CERN Document Server

    Denz, Cornelia; Kivshar, Yuri S

    2010-01-01

    Optical information processing of the future is associated with a new generation of compact nanoscale optical devices operating entirely with light. Moreover, adaptive features such as self-guiding, reconfiguration and switching become more and more important. Nonlinear devices offer an enormous potential for these applications. Consequently, innovative concepts for all-optical communication and information technologies based on nonlinear effects in photonic-crystal physics and nanoscale devices as metamaterials are of high interest. This book focuses on nonlinear optical phenomena in periodic media, such as photonic crystals, optically-induced, adaptive lattices, atomic lattices or metamaterials. The main purpose is to describe and overview new physical phenomena that result from the interplay between nonlinearities and structural periodicities and is a guide to actual and future developments for the expert reader in optical information processing, as well as in the physics of cold atoms in optical lattices.

  10. Metamaterial Embedded Wearable Rectangular Microstrip Patch Antenna

    Directory of Open Access Journals (Sweden)

    J. G. Joshi

    2012-01-01

    Full Text Available This paper presents an indigenous low-cost metamaterial embedded wearable rectangular microstrip patch antenna using polyester substrate for IEEE 802.11a WLAN applications. The proposed antenna resonates at 5.10 GHz with a bandwidth and gain of 97 MHz and 4.92 dBi, respectively. The electrical size of this antenna is 0.254λ×0.5λ. The slots are cut in rectangular patch to reduce the bending effect. This leads to mismatch the impedance at WLAN frequency band; hence, a metamaterial square SRR is embedded inside the slot. A prototype antenna has been fabricated and tested, and the measured results are presented in this paper. The simulated and measured results of the proposed antenna are found to be in good agreement. The bending effect on the performance of this antenna is experimentally verified.

  11. Terahertz broadband polarization converter based on metamaterials

    Science.gov (United States)

    Li, Yonghua; Zhao, Guozhong

    2018-01-01

    Based on the metamaterial composed of symmetrical split resonant ring, a broadband reflective terahertz polarization converter is proposed. The numerical simulation shows that it can rotate the polarization direction of linear polarized wave 90° in the range of 0.7-1.8THz and the polarization conversion ratio is over 90%. The reflection coefficient of the two electric field components in the diagonal direction is the same and the phase difference is 180° ,which leads to the cross-polarization rotation.In order to further study the physical mechanism of high polarization conversion, we analyze the surface current distribution of the resonant ring. The polarization converter has potential applications in terahertz wave plate and metamaterial antenna design.

  12. A polarization independent electromagnetically induced transparency-like metamaterial with large group delay and delay-bandwidth product

    Science.gov (United States)

    Bagci, Fulya; Akaoglu, Baris

    2018-05-01

    In this study, a classical analogue of electromagnetically induced transparency (EIT) that is completely independent of the polarization direction of the incident waves is numerically and experimentally demonstrated. The unit cell of the employed planar symmetric metamaterial structure consists of one square ring resonator and four split ring resonators (SRRs). Two different designs are implemented in order to achieve a narrow-band and wide-band EIT-like response. In the unit cell design, a square ring resonator is shown to serve as a bright resonator, whereas the SRRs behave as a quasi-dark resonator, for the narrow-band (0.55 GHz full-width at half-maximum bandwidth around 5 GHz) and wide-band (1.35 GHz full-width at half-maximum bandwidth around 5.7 GHz) EIT-like metamaterials. The observed EIT-like transmission phenomenon is theoretically explained by a coupled-oscillator model. Within the transmission window, steep changes of the phase result in high group delays and the delay-bandwidth products reach 0.45 for the wide-band EIT-like metamaterial. Furthermore, it has been demonstrated that the bandwidth and group delay of the EIT-like band can be controlled by changing the incidence angle of electromagnetic waves. These features enable the proposed metamaterials to achieve potential applications in filtering, switching, data storing, and sensing.

  13. Graphene-Enhanced Metamaterials for THz Applications

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Khromova, Irina; Zhukovsky, Sergei

    2016-01-01

    Terahertz (THz) radiation is gaining momentum in biology, medicine, communication, security, chemistry, and spectroscopy applications. To expand the usability of terahertz radiation the man-made metal-dielectric composite metamaterials are typically considered owing to their ability to effectively...... manipulate electromagnetic waves. The possibilities of light manipulation can be extended even more by involving new active materials as a structural component – such as, for example, graphene. Its prominent conductivity tunability through the electrochemical potential change allows converting a multilayer...

  14. Hybrid Metamaterials for Solar Biofuel Generation

    Science.gov (United States)

    2014-10-30

    transfer. The designed charge separation domain will be benignly expressed in bacteria as a chimera with naturally occurring protein domains which...form useful to humankind. Biosolar energy research has begun to modify photosynthetic bacteria , algae, or plants to carry out more efficient...commercial applications. Figure 7 shows four oriented metamaterial polarizers/ lenses without light illuminating the backside (Fig. 7A) and with light

  15. Hyperbolic metamaterial lens with hydrodynamic nonlocal response

    OpenAIRE

    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 free-electron plasma in the metal constituents. We derive the nonlocal corrections to the effective material parameters analytically, and illustrate the noticeable nonlocal effects on the dispersion cu...

  16. Extreme chirality in Swiss roll metamaterials

    International Nuclear Information System (INIS)

    Demetriadou, A; Pendry, J B

    2009-01-01

    The chiral Swiss roll metamaterial is a resonant, magnetic medium that exhibits a negative refractive band for one-wave polarization. Its unique structure facilitates huge chiral effects: a plane polarized wave propagating through this system can change its polarization by 90 deg. in less than a wavelength. Such chirality is at least 100 times greater than previous structures have achieved. In this paper, we discuss this extreme chiral behaviour with both numerical and analytical results.

  17. Casimir effect in the presence of metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Kort-Kamp, W.J.M.; Pinheiro, F.A.; Maia Neto, P.A.; Farina, C. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Rosa, F.S.S. [Universite Paris-Sud (France). Lab. Charles Fabry

    2011-07-01

    Full text: The Casimir effect was theoretically predicted in 1948 by H. G. B. Casimir. In its original form, it is the attraction between two parallel plates made of perfectly conductors in vacuum. The novelty in the Casimir result was the method used and not the fact that two neutral bodies attract each other, since the force between two neutral, but polarizable, atoms was previously treated by London in 1930. Casimir demonstrated that the force between the plates could be calculated from the variation in the zero-point energy of the quantized electromagnetic field caused by the presence of the plates. Nowadays there is no doubt about the existence of this effect, which has been observed in the last decade in experiments of great precision. Casimir forces play an important role in nanotechnology, in particular in the study of micro- and nano-electromechanical systems, because these forces become dominant in the nanoscopic scale. Casimir forces are responsible for an attraction of individual parts of these devices, making them eventually to stick together. As a result, attractive Casimir forces constitute a nuisance for practical applications. Therefore the investigation of a repulsive Casimir force is of great current interest. It has been recently argued that Casimir repulsion could be obtained by an adequate choice of artificial materials, the so-called metamaterials, with engineered electromagnetic properties [R. Zhao et al, PRL 103, 103602 (2009)]. In this work we investigate the interaction between an atom and a chiral metamaterial plate. Using realistic parameters, obtained from recent experiments and computer simulations, we show that state-of-the-art chiral metamaterials are not able generate Casimir repulsive forces. We also investigate the possibility of magneto-optical metamaterials to exhibit a repulsive Casimir force. To accomplish this, we discuss the dispersive interaction between a magneto-optical sphere and a chiral surface or a magneto

  18. An IoT virtualization Framework for Fast and Lossless Communication

    DEFF Research Database (Denmark)

    Patil, Sulakshana; Mihovska, Albena D.; Prasad, Ramjee

    2014-01-01

    enough and lossless. The virtualization of the network allows for low computational complexity and improved processing efficiency. The various contributions have been made in the applications that were found by IoT. The proposed global framework controls data transmission delay, reduces the data loss......An internet of things (IoT) scenario is characterized by heterogeneity found in the types of participating nodes, networks and type of data exchange. This creates a complicated scenario in relation to decision making, management and reliability. The proposed paper focuses on the design...

  19. Development and assessment of compression technique for medical images using neural network. I. Assessment of lossless compression

    International Nuclear Information System (INIS)

    Fukatsu, Hiroshi

    2007-01-01

    This paper describes assessment of the lossless compression of a new efficient compression technique (JIS system) using neural network that the author and co-workers have recently developed. At first, theory is explained for encoding and decoding the data. Assessment is done on 55 images each of chest digital roentgenography, digital mammography, 64-row multi-slice CT, 1.5 Tesla MRI, positron emission tomography (PET) and digital subtraction angiography, which are lossless-compressed by the present JIS system to see the compression rate and loss. For comparison, those data are also JPEG lossless-compressed. Personal computer (PC) is an Apple MacBook Pro with configuration of Boot Camp for Windows environment. The present JIS system is found to have a more than 4 times higher efficiency than the usual compressions which compressing the file volume to only 1/11 in average, and thus to be importantly responsible to the increasing medical imaging data. (R.T.)

  20. Elastic metamaterials and dynamic homogenization: a review

    Directory of Open Access Journals (Sweden)

    Ankit Srivastava

    2015-01-01

    Full Text Available In this paper, we review the recent advances which have taken place in the understanding and applications of acoustic/elastic metamaterials. Metamaterials are artificially created composite materials which exhibit unusual properties that are not found in nature. We begin with presenting arguments from discrete systems which support the case for the existence of unusual material properties such as tensorial and/or negative density. The arguments are then extended to elastic continuums through coherent averaging principles. The resulting coupled and nonlocal homogenized relations, called the Willis relations, are presented as the natural description of inhomogeneous elastodynamics. They are specialized to Bloch waves propagating in periodic composites and we show that the Willis properties display the unusual behavior which is often required in metamaterial applications such as the Veselago lens. We finally present the recent advances in the area of transformation elastodynamics, charting its inspirations from transformation optics, clarifying its particular challenges, and identifying its connection with the constitutive relations of the Willis and the Cosserat types.

  1. Elastic metamaterial beam with remotely tunable stiffness

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Wei [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Yu, Zhengyue [School of Naval Architecture, Ocean & Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang, Xiaole [School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Lai, Yun [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Yellen, Benjamin B., E-mail: yellen@duke.edu [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Department of Mechanical Engineering and Materials Science, Duke University, P.O. Box 90300, Hudson Hall, Durham, North Carolina 27708 (United States)

    2016-02-07

    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.

  2. 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.

  3. Review of Recent Metamaterial Microfluidic Sensors.

    Science.gov (United States)

    Salim, Ahmed; Lim, Sungjoon

    2018-01-15

    Metamaterial elements/arrays exhibit a sensitive response to fluids yet with a small footprint, therefore, they have been an attractive choice to realize various sensing devices when integrated with microfluidic technology. Micro-channels made from inexpensive biocompatible materials avoid any contamination from environment and require only microliter-nanoliter sample for sensing. Simple design, easy fabrication process, light weight prototype, and instant measurements are advantages as compared to conventional (optical, electrochemical and biological) sensing systems. Inkjet-printed flexible sensors find their utilization in rapidly growing wearable electronics and health-monitoring flexible devices. Adequate sensitivity and repeatability of these low profile microfluidic sensors make them a potential candidate for point-of-care testing which novice patients can use reliably. Aside from degraded sensitivity and lack of selectivity in all practical microwave chemical sensors, they require an instrument, such as vector network analyzer for measurements and not readily available as a self-sustained portable sensor. This review article presents state-of-the-art metamaterial inspired microfluidic bio/chemical sensors (passive devices ranging from gigahertz to terahertz range) with an emphasis on metamaterial sensing circuit and microfluidic detection. We also highlight challenges and strategies to cope these issues which set future directions.

  4. Review of Recent Metamaterial Microfluidic Sensors

    Directory of Open Access Journals (Sweden)

    Ahmed Salim

    2018-01-01

    Full Text Available Metamaterial elements/arrays exhibit a sensitive response to fluids yet with a small footprint, therefore, they have been an attractive choice to realize various sensing devices when integrated with microfluidic technology. Micro-channels made from inexpensive biocompatible materials avoid any contamination from environment and require only microliter–nanoliter sample for sensing. Simple design, easy fabrication process, light weight prototype, and instant measurements are advantages as compared to conventional (optical, electrochemical and biological sensing systems. Inkjet-printed flexible sensors find their utilization in rapidly growing wearable electronics and health-monitoring flexible devices. Adequate sensitivity and repeatability of these low profile microfluidic sensors make them a potential candidate for point-of-care testing which novice patients can use reliably. Aside from degraded sensitivity and lack of selectivity in all practical microwave chemical sensors, they require an instrument, such as vector network analyzer for measurements and not readily available as a self-sustained portable sensor. This review article presents state-of-the-art metamaterial inspired microfluidic bio/chemical sensors (passive devices ranging from gigahertz to terahertz range with an emphasis on metamaterial sensing circuit and microfluidic detection. We also highlight challenges and strategies to cope these issues which set future directions.

  5. 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.

  6. 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)

  7. 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.

  8. 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.

  9. Magnetic response of split-ring resonator metamaterials: From ...

    Indian Academy of Sciences (India)

    finally becomes comparable to the size of the unit cell of the metamaterial. In the intermediate stages ... metamaterials has been explained using an LC-circuit paradigm [4]. SRR, or its vari- ..... becomes truly problematic here. The second gap ...

  10. Theoretical modeling of critical temperature increase in metamaterial superconductors

    Science.gov (United States)

    Smolyaninov, Igor; Smolyaninova, Vera

    Recent experiments have demonstrated that the metamaterial approach is capable of drastic increase of the critical temperature Tc of epsilon near zero (ENZ) metamaterial superconductors. For example, tripling of the critical temperature has been observed in Al-Al2O3 ENZ core-shell metamaterials. Here, we perform theoretical modelling of Tc increase in metamaterial superconductors based on the Maxwell-Garnett approximation of their dielectric response function. Good agreement is demonstrated between theoretical modelling and experimental results in both aluminum and tin-based metamaterials. Taking advantage of the demonstrated success of this model, the critical temperature of hypothetic niobium, MgB2 and H2S-based metamaterial superconductors is evaluated. The MgB2-based metamaterial superconductors are projected to reach the liquid nitrogen temperature range. In the case of an H2S-based metamaterial Tc appears to reach 250 K. This work was supported in part by NSF Grant DMR-1104676 and the School of Emerging Technologies at Towson University.

  11. Experimental Verification of Plasmonic Cloaking at Microwave Frequencies with Metamaterials

    International Nuclear Information System (INIS)

    Edwards, Brian; Engheta, Nader; Alu, Andrea; Silveirinha, Mario G.

    2009-01-01

    Plasmonic cloaking is a scattering-cancellation technique based on the local negative polarizability of metamaterials. Here we report its first experimental realization and measurement at microwave frequencies. An array of metallic fins embedded in a high-permittivity fluid has been used to create a metamaterial plasmonic shell capable of cloaking a dielectric cylinder, yielding over 75% reduction of total scattering width.

  12. 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 ...

  13. Optically active Babinet planar metamaterial film for terahertz polarization manipulation

    DEFF Research Database (Denmark)

    Zalkovskij, Maksim; Malureanu, Radu; Kremers, C.

    2013-01-01

    A planar Babinet-inverted dimer metamaterial possessing strong optical activity is proposed and characterized. An original fabrication method to produce large area (up to several cm2) freely suspended flexible metallic membranes is implemented to fabricate the metamaterial. Its optical properties...

  14. Experimental demonstration of metamaterial "multiverse" in a ferrofluid.

    Science.gov (United States)

    Smolyaninov, Igor I; Yost, Bradley; Bates, Evan; Smolyaninova, Vera N

    2013-06-17

    Extraordinary light rays propagating inside a hyperbolic metamaterial look similar to particle world lines in a 2 + 1 dimensional Minkowski spacetime. Magnetic nanoparticles in a ferrofluid are known to form nanocolumns aligned along the magnetic field, so that a hyperbolic metamaterial may be formed at large enough nanoparticle concentration nH. Here we investigate optical properties of such a metamaterial just below nH. While on average such a metamaterial is elliptical, thermal fluctuations of nanoparticle concentration lead to transient formation of hyperbolic regions (3D Minkowski spacetimes) inside this metamaterial. Thus, thermal fluctuations in a ferrofluid look similar to creation and disappearance of individual Minkowski spacetimes (universes) in the cosmological multiverse. This theoretical picture is supported by experimental measurements of polarization-dependent optical transmission of a cobalt based ferrofluid at 1500 nm.

  15. Optically controlled redshift switching effects in hybrid fishscale metamaterials

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2018-05-01

    Full Text Available We numerically demonstrate optically controlled THz response in a hybrid fishscale metamaterial with embedded photoconductive silicon at oblique incidence of TE wave. The oblique incidence allows excitation of Fano-type trapped mode resonance in a 2-fold rotational symmetric metamaterial. The hybrid fishscale metamaterial exhibits an optically controlled redshift switching effect in the THz range. The switching effect is dominated by the conductivity of the silicon instead of mechanically adjusting angles of incidence. The tuning frequency range is up to 0.3THz with a large modulation depth and high transmission in the “ON” state. The fishscale metamaterial-based switching has been experimentally verified by its microwave counterpart integrated by variable resistors. Our work provides an alternative route to realize tunable Fano-type response in metamaterials and is of importance to active manipulation, sensing and switching of THz waves in practical applications.

  16. Optically controlled redshift switching effects in hybrid fishscale metamaterials

    Science.gov (United States)

    Wang, Yu; Zhu, Jinwei; Zhang, Hao; Zhang, Wenxing; Dong, Guohua; Ye, Peng; Lv, Tingting; Zhu, Zheng; Li, Yuxiang; Guan, Chunying; Shi, Jinhui

    2018-05-01

    We numerically demonstrate optically controlled THz response in a hybrid fishscale metamaterial with embedded photoconductive silicon at oblique incidence of TE wave. The oblique incidence allows excitation of Fano-type trapped mode resonance in a 2-fold rotational symmetric metamaterial. The hybrid fishscale metamaterial exhibits an optically controlled redshift switching effect in the THz range. The switching effect is dominated by the conductivity of the silicon instead of mechanically adjusting angles of incidence. The tuning frequency range is up to 0.3THz with a large modulation depth and high transmission in the "ON" state. The fishscale metamaterial-based switching has been experimentally verified by its microwave counterpart integrated by variable resistors. Our work provides an alternative route to realize tunable Fano-type response in metamaterials and is of importance to active manipulation, sensing and switching of THz waves in practical applications.

  17. Double-negative metamaterial for mobile phone application

    Science.gov (United States)

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

    2017-01-01

    In this paper, a new design and analysis of metamaterial and its applications to modern handset are presented. The proposed metamaterial unit-cell design consists of two connected square spiral structures, which leads to increase the effective media ratio. The finite instigation technique based on Computer Simulation Technology Microwave Studio is utilized in this investigation, and the measurement is taken in an anechoic chamber. A good agreement is observed among simulated and measured results. The results indicate that the proposed metamaterial can successfully cover cellular phone frequency bands. Moreover, the uses of proposed metamaterial in modern handset antennas are also analyzed. The results reveal that the proposed metamaterial attachment significantly reduces specific absorption rate values without reducing the antenna performances.

  18. Nanoparticles doped film sensing based on terahertz metamaterials

    Science.gov (United States)

    Liu, Weimin; Fan, Fei; Chang, Shengjiang; Hou, Jiaqing; Chen, Meng; Wang, Xianghui; Bai, Jinjun

    2017-12-01

    A nanoparticles concentration sensor based on doped film and terahertz (THz) metamaterial has been proposed. By coating the nanoparticles doped polyvinyl alcohol (PVA) film on the surface of THz metamaterial, the effects of nanoparticle concentration on the metamaterial resonances are investigated through experiments and numerical simulations. Results show that resonant frequency of the metamaterial linearly decreases with the increment of doping concentration. Furthermore, numerical simulations illustrate that the redshift of resonance results from the changes of refractive index of the doped film. The concentration sensitivity of this sensor is 3.12 GHz/0.1%, and the refractive index sensitivity reaches 53.33 GHz/RIU. This work provides a non-contact, nondestructive and sensitive method for the detection of nanoparticles concentration and brings out a new application on THz film metamaterial sensing.

  19. Low-SAR metamaterial-inspired printed monopole antenna

    Science.gov (United States)

    Hossain, M. I.; Faruque, M. R. I.; Islam, M. T.; Ali, M. T.

    2017-01-01

    In this paper, a low-SAR metamaterial-embedded planar monopole antenna is introduced for a wireless communication system. A printed monopole antenna is designed for modern mobile, which operates in GSM, UMTS, LTE, WLAN, and Bluetooth frequency bands. A metamaterial structure is designed to use in the mobile handset with a multi-band printed monopole antenna. The finite integration technique of the CST microwave studio is used in this study. The measurement of antenna performances is taken in an anechoic chamber, and the SAR values are measured using COMOSAR system. The results indicate that metamaterial structure leads to reduce SAR without affecting antenna performance significantly. According to the measured results, the metamaterial attachment leads to reduce 87.7% peak SAR, 68.2% 1-g SAR, and 46.78% 10-g SAR compared to antenna without metamaterial.

  20. Active Metamaterials for Terahertz Communication and Imaging

    Science.gov (United States)

    Rout, Saroj

    In recent years there has been significant interest in terahertz (THz) systems mostly due to their unique applications in communication and imaging. One of the primary reason for this resurgence is the use of metamaterials to design THz devices due to lack of natural materials that can respond to this electromagnetic spectrum, the so-called ''THz gap''. Even after years of intense research, THz systems are complex and expensive, unsuitable for mainstream applications. This work focuses on bridging this gap by building all solid-state THz devices for imaging and communication applications in a commercial integrated circuit (IC) technology. One such canonical device is a THz wave modulator that can be used in THz wireless communication devices and as spatial light modulator (SLM) for THz imaging systems. The key contribution of this thesis is a metamaterial based THz wave modulator fabricated in a commercial gallium arsenide (GaAs) process resonant at 0.46 THz using a novel approach of embedding pseudomorphic high electron mobility transistors (pHEMTs) in metamaterial and demonstrate modulation values over 30%, and THz modulation at frequencies up to 10 MHz. Using the THz wave modulator, we fabricated and experimentally demonstrated an all solid-state metamaterial based THz spatial light modulator (SLM) as a 2x2 pixel array operating around 0.46 THz, by raster scanning an occluded metal object in polystyrene using a single-pixel imaging setup. This was an important step towards building an low-voltage (1V), low power, on-chip integrable THz imaging device. Using the characterization result from the THz SLM, we computationally demonstrated a multi-level amplitude shift keying (ASK) terahertz wireless communication system using spatial light modulation instead of traditional voltage mode modulation, achieving higher spectral efficiency for high speed communication. We show two orders of magnitude improvement in symbol error rate (SER) for a degradation of 20 dB in

  1. 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

  2. Clustered DPCM with removing noise spectra for the lossless compression of hyperspectral images

    Science.gov (United States)

    Wu, Jiaji; Xu, Jianglei

    2013-10-01

    The clustered DPCM (C-DPCM) lossless compression method by Jarno et al. for hyperspectral images achieved a good compression effect. It can be divided into three components: clustering, prediction, and coding. In the prediction part, it solves a multiple linear regression model for each of the clusters in every band. Without considering the effect of noise spectra, there is still room for improvement. This paper proposes a C-DPCM method with Removing Noise Spectra (C-DPCM-RNS) for the lossless compression of hyperspectral images. C-DPCM-RNS's prediction part consists of two-times trainings. The prediction coefficients obtained from the first training will be used in the linear predictor to compute all the predicted values and then the difference between original and predicted values in current band of current class. Only the non-noise spectra are used in the second training. The resulting prediction coefficients from the second training will be used for prediction and sent to the decoder. The two-times trainings remove part of the interference of noise spectra, and reaches a better compression effect than other methods based on regression prediction.

  3. Ion Elevators and Escalators in Multilevel Structures for Lossless Ion Manipulations

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Yehia M.; Hamid, Ahmed M.; Cox, Jonathan T.; Garimella, Venkata BS; Smith, Richard D.

    2017-01-19

    We describe two approaches based upon ion ‘elevator’ and ‘escalator’ components that allow moving ions to different levels in structures for lossless ion manipulations (SLIM). Guided by ion motion simulations we designed elevator and escalator components providing essentially lossless transmission in multi-level designs based upon ion current measurements. The ion elevator design allowed ions to efficiently bridge a 4 mm gap between levels. The component was integrated in a SLIM and coupled to a QTOF mass spectrometer using an ion funnel interface to evaluate the m/z range transmitted as compared to transmission within a level (e.g. in a linear section). Mass spectra for singly-charged ions of m/z 600-2700 produced similar mass spectra for both elevator and straight (linear motion) components. In the ion escalator design, traveling waves (TW) were utilized to transport ions efficiently between two SLIM levels. Ion current measurements and ion mobility (IM) spectrometry analysis illustrated that ions can be transported between TW-SLIM levels with no significant loss of either ions or IM resolution. These developments provide a path for the development of multilevel designs providing e.g. much longer IM path lengths, more compact designs, and the implementation of much more complex SLIM devices in which e.g. different levels may operate at different temperatures or with different gases.

  4. Ion Elevators and Escalators in Multilevel Structures for Lossless Ion Manipulations.

    Science.gov (United States)

    Ibrahim, Yehia M; Hamid, Ahmed M; Cox, Jonathan T; Garimella, Sandilya V B; Smith, Richard D

    2017-02-07

    We describe two approaches based upon ion "elevator" and "escalator" components that allow moving ions to different levels in structures for lossless ion manipulations (SLIM). Guided by ion motion simulations, we designed elevator and escalator components based upon ion current measurements providing essentially lossless transmission in multilevel designs. The ion elevator design allowed ions to efficiently bridge a 4 mm gap between levels. The component was integrated in a SLIM and coupled to a QTOF mass spectrometer using an ion funnel interface to evaluate the m/z range transmitted as compared to transmission within a level (e.g., in a linear section). The analysis of singly charged ions of m/z 600-2700 produced similar mass spectra for both elevator and straight (linear motion) components. In the ion escalator design, traveling waves (TW) were utilized to transport ions efficiently between two SLIM levels. Ion current measurements and ion mobility (IM) spectrometry analysis illustrated that ions can be transported between TW-SLIM levels with no significant loss of either ions or IM resolution. These developments provide a path for the development of multilevel designs providing, e.g., much longer IM path lengths, more compact designs, and the implementation of much more complex SLIM devices in which, e.g., different levels may operate at different temperatures or with different gases.

  5. Combination of Sharing Matrix and Image Encryption for Lossless $(k,n)$ -Secret Image Sharing.

    Science.gov (United States)

    Bao, Long; Yi, Shuang; Zhou, Yicong

    2017-12-01

    This paper first introduces a (k,n) -sharing matrix S (k, n) and its generation algorithm. Mathematical analysis is provided to show its potential for secret image sharing. Combining sharing matrix with image encryption, we further propose a lossless (k,n) -secret image sharing scheme (SMIE-SIS). Only with no less than k shares, all the ciphertext information and security key can be reconstructed, which results in a lossless recovery of original information. This can be proved by the correctness and security analysis. Performance evaluation and security analysis demonstrate that the proposed SMIE-SIS with arbitrary settings of k and n has at least five advantages: 1) it is able to fully recover the original image without any distortion; 2) it has much lower pixel expansion than many existing methods; 3) its computation cost is much lower than the polynomial-based secret image sharing methods; 4) it is able to verify and detect a fake share; and 5) even using the same original image with the same initial settings of parameters, every execution of SMIE-SIS is able to generate completely different secret shares that are unpredictable and non-repetitive. This property offers SMIE-SIS a high level of security to withstand many different attacks.

  6. Lossless Geometry Compression Through Changing 3D Coordinates into 1D

    Directory of Open Access Journals (Sweden)

    Yongkui Liu

    2013-08-01

    Full Text Available A method of lossless geometry compression on the coordinates of the vertexes for grid model is presented. First, the 3D coordinates are pre-processed to be transformed into a specific form. Then these 3D coordinates are changed into 1D data by making the three coordinates of a vertex represented by only a position number, which is made of a large integer. To minimize the integers, they are sorted and the differences between two adjacent vertexes are stored in a vertex table. In addition to the technique of geometry compression on coordinates, an improved method for storing the compressed topological data in a facet table is proposed to make the method more complete and efficient. The experimental results show that the proposed method has a better compression rate than the latest method of lossless geometry compression, the Isenburg-Lindstrom-Snoeyink method. The theoretical analysis and the experiment results also show that the important decompression time of the new method is short. Though the new method is explained in the case of a triangular grid, it can also be used in other forms of grid model.

  7. Research on lossless compression of true color RGB image with low time and space complexity

    Science.gov (United States)

    Pan, ShuLin; Xie, ChengJun; Xu, Lin

    2008-12-01

    Eliminating correlated redundancy of space and energy by using a DWT lifting scheme and reducing the complexity of the image by using an algebraic transform among the RGB components. An improved Rice Coding algorithm, in which presents an enumerating DWT lifting scheme that fits any size images by image renormalization has been proposed in this paper. This algorithm has a coding and decoding process without backtracking for dealing with the pixels of an image. It support LOCO-I and it can also be applied to Coder / Decoder. Simulation analysis indicates that the proposed method can achieve a high image compression. Compare with Lossless-JPG, PNG(Microsoft), PNG(Rene), PNG(Photoshop), PNG(Anix PicViewer), PNG(ACDSee), PNG(Ulead photo Explorer), JPEG2000, PNG(KoDa Inc), SPIHT and JPEG-LS, the lossless image compression ratio improved 45%, 29%, 25%, 21%, 19%, 17%, 16%, 15%, 11%, 10.5%, 10% separately with 24 pieces of RGB image provided by KoDa Inc. Accessing the main memory in Pentium IV,CPU2.20GHZ and 256MRAM, the coding speed of the proposed coder can be increased about 21 times than the SPIHT and the efficiency of the performance can be increased 166% or so, the decoder's coding speed can be increased about 17 times than the SPIHT and the efficiency of the performance can be increased 128% or so.

  8. Irreversible JPEG 2000 compression of abdominal CT for primary interpretation: assessment of visually lossless threshold

    International Nuclear Information System (INIS)

    Lee, Kyoung Ho; Kim, Young Hoon; Kim, Bo Hyoung; Kim, Kil Joong; Kim, Tae Jung; Kim, Hyuk Jung; Hahn, Seokyung

    2007-01-01

    To estimate the visually lossless threshold for Joint Photographic Experts Group (JPEG) 2000 compression of contrast-enhanced abdominal computed tomography (CT) images, 100 images were compressed to four different levels: a reversible (as negative control) and irreversible 5:1, 10:1, and 15:1. By alternately displaying the original and the compressed image on the same monitor, six radiologists independently determined if the compressed image was distinguishable from the original image. For each reader, we compared the proportion of the compressed images being rated distinguishable from the original images between the reversible compression and each of the three irreversible compressions using the exact test for paired proportions. For each reader, the proportion was not significantly different between the reversible (0-1%, 0/100 to 1/100) and irreversible 5:1 compression (0-3%). However, the proportion significantly increased with the irreversible 10:1 (95-99%) and 15:1 compressions (100%) versus reversible compression in all readers (P < 0.001); 100 and 95% of the 5:1 compressed images were rated indistinguishable from the original images by at least five of the six readers and all readers, respectively. Irreversibly 5:1 compressed abdominal CT images are visually lossless and, therefore, potentially acceptable for primary interpretation. (orig.)

  9. Empirical and Statistical Evaluation of the Effectiveness of Four Lossless Data Compression Algorithms

    Directory of Open Access Journals (Sweden)

    N. A. Azeez

    2017-04-01

    Full Text Available Data compression is the process of reducing the size of a file to effectively reduce storage space and communication cost. The evolvement in technology and digital age has led to an unparalleled usage of digital files in this current decade. The usage of data has resulted to an increase in the amount of data being transmitted via various channels of data communication which has prompted the need to look into the current lossless data compression algorithms to check for their level of effectiveness so as to maximally reduce the bandwidth requirement in communication and transfer of data. Four lossless data compression algorithm: Lempel-Ziv Welch algorithm, Shannon-Fano algorithm, Adaptive Huffman algorithm and Run-Length encoding have been selected for implementation. The choice of these algorithms was based on their similarities, particularly in application areas. Their level of efficiency and effectiveness were evaluated using some set of predefined performance evaluation metrics namely compression ratio, compression factor, compression time, saving percentage, entropy and code efficiency. The algorithms implementation was done in the NetBeans Integrated Development Environment using Java as the programming language. Through the statistical analysis performed using Boxplot and ANOVA and comparison made on the four algo

  10. Real-time lossless data compression techniques for long-pulse operation

    International Nuclear Information System (INIS)

    Vega, J.; Ruiz, M.; Sanchez, E.; Pereira, A.; Portas, A.; Barrera, E.

    2007-01-01

    Data logging and data distribution will be two main tasks connected with data handling in ITER. Data logging refers to the recovery and ultimate storage of all data, independent of the data source. Data distribution is related, on the one hand, to the on-line data broadcasting for immediate data availability and, on the other hand, to the off-line data access. Due to the large data volume expected, data compression is a useful candidate to prevent the waste of resources in communication and storage systems. On-line data distribution in a long-pulse environment requires the use of a deterministic approach to be able to ensure a proper response time for data availability. However, an essential feature for all the above purposes is to apply lossless compression techniques. This article reviews different lossless data compression techniques based on delta compression. In addition, the concept of cyclic delta transformation is introduced. Furthermore, comparative results concerning compression rates on different databases (TJ-II and JET) and computation times for compression/decompression are shown. Finally, the validity and implementation of these techniques for long-pulse operation and real-time requirements is also discussed

  11. Real-time lossless data compression techniques for long-pulse operation

    Energy Technology Data Exchange (ETDEWEB)

    Vega, J. [Asociacion EURATOM/CIEMAT para Fusion, Avda. Complutense 22, 28040 Madrid (Spain)], E-mail: jesus.vega@ciemat.es; Ruiz, M. [Dpto. de Sistemas Electronicos y de Control, UPM, Campus Sur. Ctra., Valencia km 7, 28031 Madrid (Spain); Sanchez, E.; Pereira, A.; Portas, A. [Asociacion EURATOM/CIEMAT para Fusion, Avda. Complutense 22, 28040 Madrid (Spain); Barrera, E. [Dpto. de Sistemas Electronicos y de Control, UPM, Campus Sur. Ctra., Valencia km 7, 28031 Madrid (Spain)

    2007-10-15

    Data logging and data distribution will be two main tasks connected with data handling in ITER. Data logging refers to the recovery and ultimate storage of all data, independent of the data source. Data distribution is related, on the one hand, to the on-line data broadcasting for immediate data availability and, on the other hand, to the off-line data access. Due to the large data volume expected, data compression is a useful candidate to prevent the waste of resources in communication and storage systems. On-line data distribution in a long-pulse environment requires the use of a deterministic approach to be able to ensure a proper response time for data availability. However, an essential feature for all the above purposes is to apply lossless compression techniques. This article reviews different lossless data compression techniques based on delta compression. In addition, the concept of cyclic delta transformation is introduced. Furthermore, comparative results concerning compression rates on different databases (TJ-II and JET) and computation times for compression/decompression are shown. Finally, the validity and implementation of these techniques for long-pulse operation and real-time requirements is also discussed.

  12. Implementation of a perfect metamaterial absorber into multi-functional sensor applications

    Science.gov (United States)

    Akgol, O.; Karaaslan, M.; Unal, E.; Sabah, C.

    2017-05-01

    Perfect metamaterial absorber (MA)-based sensor applications are presented and investigated in the microwave frequency range. It is also experimentally analyzed and tested to verify the behavior of the MA. Suggested perfect MA-based sensor has a simple configuration which introduces flexibility to sense the dielectric properties of a material and the pressure of the medium. The investigated applications include pressure and density sensing. Besides, numerical simulations verify that the suggested sensor achieves good sensing capabilities for both applications. The proposed perfect MA-based sensor variations enable many potential applications in medical or food technologies.

  13. Design of a Lossless Image Compression System for Video Capsule Endoscopy and Its Performance in In-Vivo Trials

    Science.gov (United States)

    Khan, Tareq H.; Wahid, Khan A.

    2014-01-01

    In this paper, a new low complexity and lossless image compression system for capsule endoscopy (CE) is presented. The compressor consists of a low-cost YEF color space converter and variable-length predictive with a combination of Golomb-Rice and unary encoding. All these components have been heavily optimized for low-power and low-cost and lossless in nature. As a result, the entire compression system does not incur any loss of image information. Unlike transform based algorithms, the compressor can be interfaced with commercial image sensors which send pixel data in raster-scan fashion that eliminates the need of having large buffer memory. The compression algorithm is capable to work with white light imaging (WLI) and narrow band imaging (NBI) with average compression ratio of 78% and 84% respectively. Finally, a complete capsule endoscopy system is developed on a single, low-power, 65-nm field programmable gate arrays (FPGA) chip. The prototype is developed using circular PCBs having a diameter of 16 mm. Several in-vivo and ex-vivo trials using pig's intestine have been conducted using the prototype to validate the performance of the proposed lossless compression algorithm. The results show that, compared with all other existing works, the proposed algorithm offers a solution to wireless capsule endoscopy with lossless and yet acceptable level of compression. PMID:25375753

  14. 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)

  15. 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 < 100 fs) and a change in resistivity of four orders or more make vanadium dioxide (VO2) an ideal candidate for active metamaterials. It is known that the 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.

  16. 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.

  17. Application of Metamaterials to RF Energy Harvesting and Infrared Photodetection

    Science.gov (United States)

    Fowler, Clayton M.

    Techniques for adapting metamaterials for the improvement of RF energy harvesting and infrared photodetection are demonstrated using experimental and computer simulation methods. Two methods for RF energy harvesting are experimentally demonstrated and supported by computer simulation. In the first method, a metamaterial perfect absorber (MPA) is made into a rectenna capable of harvesting RF energy and delivering power to a load by soldering Schottky diodes onto connected split ring resonator (SRR) structures composing the planar metasurface of the perfect absorber. The metamaterial rectenna is accompanied by a ground plane placed parallel to it, which forms a Fabry-Perot cavity between the metasurface and the ground plane. The Fabry-Perot cavity stores energy in the form of standing waves which is transferred to the SRR structures of the metasurface as AC currents that are rectified by the diodes to create DC power. This type of design enables highly efficient energy harvesting for low input power, creates a large antenna capture area, and uses elements with small electrical size, such that 100 uW of power (enough to operate simple devices) can be captured at ambient intensities 1 - 2 uW/cm2. Two designs using this method are presented, one that operates for linear polarizations at 0.9 GHz and a smaller polarization-independent design that operates around 1.5 GHz. In the second method, the energy stored in the standing waves of an MPA Fabry-Perot cavity is instead harvested by placing a separate energy harvesting antenna within the cavity. The cavity shapes and enhances the incident electric field, and then the separate energy harvesting antenna is designed to be inserted into the cavity so that its shape and/or radiation pattern matches the electric field lines within the cavity and maximally extracts the stored energy. This method allows for great customization of antenna design parameters, such as operating frequency, polarization dependence, and directionality

  18. Dielectric optical antenna thermal emitters and metamaterials

    Science.gov (United States)

    Schuller, Jonathan Aaron

    Optical antennas are critical components in nanophotonics research due to their unparalleled ability to concentrate electromagnetic energy into nanoscale volumes. Researchers typically construct such antennas from wavelength-size metallic structures. However, recent research has begun to exploit the scattering resonances of high-permittivity particles to realize all-dielectric optical antennas, emitters, and metamaterials. In this thesis, we experimentally and theoretically characterize the resonant modes of subwavelength rod-shaped dielectric particles and demonstrate their use in negative index metamaterials and novel infrared light emitters. At mid-infrared frequencies, Silicon Carbide (SiC) is an ideal system for studying the behavior of dielectric optical antennas. At frequencies below the TO phonon resonance, SiC behaves like a dielectric with very large refractive index. Using infrared spectroscopy and analytical Mie calculations we show that individual rod-shaped SiC particles exhibit a multitude of resonant modes. Detailed investigations of these SiC optical antennas reveal a wealth of new physics and applications. We discuss the distinct electromagnetic field profile for each mode, and demonstrate that two of the dielectric-type Mie resonances can be combined in a particle array to form a negative index metamaterial. We further show that these particles can serve as "broadcasting" antennas. Using a custom-built thermal emission microscope we collect emissivity spectra from single SiC particles at elevated temperatures, highlighting their use as subwavelength resonant light emitters. Finally, we derive and verify a variety of general analytical results applicable to all cylindrical dielectric antennas.

  19. Dielectric Optical Antenna Emitters and Metamaterials

    Science.gov (United States)

    Schuller, Jon

    2009-03-01

    Optical antennas are critical components in nanophotonics research due to their unparalleled ability to concentrate electromagnetic energy into nanoscale volumes. Researchers typically construct such antennas from wavelength-size metallic structures. However, recent research has begun to exploit the scattering resonances of high-permittivity particles to realize all-dielectric optical antennas, emitters, and metamaterials. In this talk, we experimentally and theoretically characterize the resonant modes of subwavelength rod-shaped dielectric particles and demonstrate their use in negative index metamaterials and novel infrared light emitters. At mid-infrared frequencies, Silicon Carbide (SiC) is an ideal system for studying the behavior of dielectric optical antennas. At frequencies below the TO phonon resonance, SiC behaves like a dielectric with very large refractive index. Using infrared spectroscopy and analytical Mie calculations we show that individual rod-shaped SiC particles exhibit a multitude of resonant modes. Detailed investigations of these SiC optical antennas reveal a wealth of new physics and applications. We discuss the distinct electromagnetic field profile for each mode, and demonstrate that two of the dielectric-type Mie resonances can be combined in a particle array to form a negative index metamaterial [1]. We further show that these particles can serve as ``broadcasting'' antennas. Using a custom-built thermal emission microscope we collect emissivity spectra from single SiC particles at elevated temperatures, highlighting their use as subwavelength resonant light emitters. Finally, we derive and verify a variety of general analytical results applicable to all cylindrical dielectric antennas and discuss extensions of the demonstrated concepts to different materials systems and frequency regimes. [1] J.A. Schuller, et al., Phys. Rev. Lett. 99, 107401 (2007)

  20. 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

  1. Thermally tunable magnetic metamaterials at THz frequencies

    International Nuclear Information System (INIS)

    Bui, Son Tung; Nguyen, Van Dung; Bui, Xuan Khuyen; Vu, Dinh Lam; Nguyen, Thanh Tung; Lievens, Peter; Lee, YoungPak

    2013-01-01

    We investigate theoretically and numerically the tunability of the magnetic property of metamaterial in the THz region via thermal control. One component of the meta-atom is InSb, playing an important role as an alterable metal. When the temperature of the InSb stack increases from 300 to 350 K, the resonance peak of the transmission spectra shows a shift from 0.6 to 0.85 THz accompanied by a stronger magnetic behavior. The S-parameter retrieval method realizes the tunability of the negative permeability achieved in the above heating range. (paper)

  2. 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.

  3. 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.

  4. 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.

  5. Electromagnetic Field Control and Optimization Using Metamaterials

    Science.gov (United States)

    2009-12-01

    Popović, and K. Hingerl. “Imperfect cloak- ing devices based on metamaterials,” Acta Physica Polonica A , 112(5):1083– 1088, 2007. 148 44. Jiang, Wei X...f. Jcpq Date Accepted: ... M ( A T~ 󈧢 S’t’P 2 GCt:f M. U. Thomas Date Dean, Graduate School of Engineering and Management APIT/DEE/ENG/09-13...dictated by the theory are inhomogeneous, anisotropic, and, in some instances, singular at various locations. In order for a cloak to be practically

  6. Permanent magnetic ferrite based power-tunable metamaterials

    Science.gov (United States)

    Zhang, Guanqiao; Lan, Chuwen; Gao, Rui; Zhou, Ji

    2017-08-01

    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.

  7. 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.

  8. A 3D Optical Metamaterial Made by Self-Assembly

    KAUST Repository

    Vignolini, Silvia; Yufa, Nataliya A.; Cunha, Pedro S.; Guldin, Stefan; Rushkin, Ilia; Stefik, Morgan; Hur, Kahyun; Wiesner, Ulrich; Baumberg, Jeremy J.; Steiner, Ullrich

    2011-01-01

    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.

  9. 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.

  10. 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.

  11. Unidirectional Wave Vector Manipulation in Two-Dimensional Space with an All Passive Acoustic Parity-Time-Symmetric Metamaterials Crystal

    Science.gov (United States)

    Liu, Tuo; Zhu, Xuefeng; Chen, Fei; Liang, Shanjun; Zhu, Jie

    2018-03-01

    Exploring the concept of non-Hermitian Hamiltonians respecting parity-time symmetry with classical wave systems is of great interest as it enables the experimental investigation of parity-time-symmetric systems through the quantum-classical analogue. Here, we demonstrate unidirectional wave vector manipulation in two-dimensional space, with an all passive acoustic parity-time-symmetric metamaterials crystal. The metamaterials crystal is constructed through interleaving groove- and holey-structured acoustic metamaterials to provide an intrinsic parity-time-symmetric potential that is two-dimensionally extended and curved, which allows the flexible manipulation of unpaired wave vectors. At the transition point from the unbroken to broken parity-time symmetry phase, the unidirectional sound focusing effect (along with reflectionless acoustic transparency in the opposite direction) is experimentally realized over the spectrum. This demonstration confirms the capability of passive acoustic systems to carry the experimental studies on general parity-time symmetry physics and further reveals the unique functionalities enabled by the judiciously tailored unidirectional wave vectors in space.

  12. Review and Implementation of the Emerging CCSDS Recommended Standard for Multispectral and Hyperspectral Lossless Image Coding

    Science.gov (United States)

    Sanchez, Jose Enrique; Auge, Estanislau; Santalo, Josep; Blanes, Ian; Serra-Sagrista, Joan; Kiely, Aaron

    2011-01-01

    A new standard for image coding is being developed by the MHDC working group of the CCSDS, targeting onboard compression of multi- and hyper-spectral imagery captured by aircraft and satellites. The proposed standard is based on the "Fast Lossless" adaptive linear predictive compressor, and is adapted to better overcome issues of onboard scenarios. In this paper, we present a review of the state of the art in this field, and provide an experimental comparison of the coding performance of the emerging standard in relation to other state-of-the-art coding techniques. Our own independent implementation of the MHDC Recommended Standard, as well as of some of the other techniques, has been used to provide extensive results over the vast corpus of test images from the CCSDS-MHDC.

  13. Performance of highly connected photonic switching lossless metro-access optical networks

    Science.gov (United States)

    Martins, Indayara Bertoldi; Martins, Yara; Barbosa, Felipe Rudge

    2018-03-01

    The present work analyzes the performance of photonic switching networks, optical packet switching (OPS) and optical burst switching (OBS), in mesh topology of different sizes and configurations. The "lossless" photonic switching node is based on a semiconductor optical amplifier, demonstrated and validated with experimental results on optical power gain, noise figure, and spectral range. The network performance was evaluated through computer simulations based on parameters such as average number of hops, optical packet loss fraction, and optical transport delay (Am). The combination of these elements leads to a consistent account of performance, in terms of network traffic and packet delivery for OPS and OBS metropolitan networks. Results show that a combination of highly connected mesh topologies having an ingress e-buffer present high efficiency and throughput, with very low packet loss and low latency, ensuring fast data delivery to the final receiver.

  14. Ion Trapping, Storage, and Ejection in Structures for Lossless Ion Manipulations.

    Science.gov (United States)

    Zhang, Xinyu; Garimella, Sandilya V B; Prost, Spencer A; Webb, Ian K; Chen, Tsung-Chi; Tang, Keqi; Tolmachev, Aleksey V; Norheim, Randolph V; Baker, Erin S; Anderson, Gordon A; Ibrahim, Yehia M; Smith, Richard D

    2015-06-16

    A new Structures for Lossless Ion Manipulations (SLIM) module, having electrode arrays patterned on a pair of parallel printed circuit boards (PCB), was constructed and utilized to investigate capabilities for ion trapping at a pressure of 4 Torr. Positive ions were confined by application of RF voltages to a series of inner rung electrodes with alternating phase on adjacent electrodes, in conjunction with positive DC potentials on surrounding guard electrodes on each PCB. An axial DC field was also introduced by stepwise varying the DC potentials applied to the inner rung electrodes to control the ion transport and accumulation inside the ion trapping region. We show that ions can be trapped and accumulated with up to 100% efficiency, stored for at least 5 h with no significant losses, and then could be rapidly ejected from the SLIM trap. The present results provide a foundation for the development of much more complex SLIM devices that facilitate extended ion manipulations.

  15. Lossless medical image compression using geometry-adaptive partitioning and least square-based prediction.

    Science.gov (United States)

    Song, Xiaoying; Huang, Qijun; Chang, Sheng; He, Jin; Wang, Hao

    2018-06-01

    To improve the compression rates for lossless compression of medical images, an efficient algorithm, based on irregular segmentation and region-based prediction, is proposed in this paper. Considering that the first step of a region-based compression algorithm is segmentation, this paper proposes a hybrid method by combining geometry-adaptive partitioning and quadtree partitioning to achieve adaptive irregular segmentation for medical images. Then, least square (LS)-based predictors are adaptively designed for each region (regular subblock or irregular subregion). The proposed adaptive algorithm not only exploits spatial correlation between pixels but it utilizes local structure similarity, resulting in efficient compression performance. Experimental results show that the average compression performance of the proposed algorithm is 10.48, 4.86, 3.58, and 0.10% better than that of JPEG 2000, CALIC, EDP, and JPEG-LS, respectively. Graphical abstract ᅟ.

  16. Development and performance analysis of a lossless data reduction algorithm for voip

    International Nuclear Information System (INIS)

    Misbahuddin, S.; Boulejfen, N.

    2014-01-01

    VoIP (Voice Over IP) is becoming an alternative way of voice communications over the Internet. To better utilize voice call bandwidth, some standard compression algorithms are applied in VoIP systems. However, these algorithms affect the voice quality with high compression ratios. This paper presents a lossless data reduction technique to improve VoIP data transfer rate over the IP network. The proposed algorithm exploits the data redundancies in digitized VFs (Voice Frames) generated by VoIP systems. Performance of proposed data reduction algorithm has been presented in terms of compression ratio. The proposed algorithm will help retain the voice quality along with the improvement in VoIP data transfer rates. (author)

  17. Topological mechanics: from metamaterials to active matter

    Science.gov (United States)

    Vitelli, Vincenzo

    2015-03-01

    Mechanical metamaterials are artificial structures with unusual properties, such as negative Poisson ratio, bistability or tunable acoustic response, which originate in the geometry of their unit cell. At the heart of such unusual behavior is often a mechanism: a motion that does not significantly stretch or compress the links between constituent elements. When activated by motors or external fields, these soft motions become the building blocks of robots and smart materials. In this talk, we discuss topological mechanisms that possess two key properties: (i) their existence cannot be traced to a local imbalance between degrees of freedom and constraints (ii) they are robust against a wide range of structural deformations or changes in material parameters. The continuum elasticity of these mechanical structures is captured by non-linear field theories with a topological boundary term similar to topological insulators and quantum Hall systems. We present several applications of these concepts to the design and experimental realization of 2D and 3D topological structures based on linkages, origami, buckling meta-materials and lastly active media that break time-reversal symmetry.

  18. One-dimensional rigid film acoustic metamaterials

    Science.gov (United States)

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

    2015-11-01

    We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves.

  19. One-dimensional rigid film acoustic metamaterials

    International Nuclear Information System (INIS)

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

    2015-01-01

    We have designed a 1D film-type acoustic metamaterial structure consisting of several polymer films directly stacked on each other. It is experimentally revealed that the mass density law can be broken by such structures in the low frequency range. By comparing the sound transmission loss (STL) curves of structures with different numbers of cycles, materials and incident sound directions, several physical properties of the 1D film-type acoustic metamaterial are revealed, which consist of cyclical effects, surface effects and orientation effects. It is suggested that the excellent low frequency sound insulation capacity is influenced by both the cycle number and the stiffness of the film surface. Meanwhile, the surface effect plays a dominant role among these physical properties. Due to the surface acoustic property, for structures with a particular combination form, the STL dominated by the cyclical effects may reach saturation with increasing number of construction periods. Moreover, in some cases, the sound insulation ability is diverse for different sound incidence directions. This kind of 1D film-type periodic structure with these special physical properties provides a new concept for the regulation of sound waves. (paper)

  20. Ultrathin microwave absorber based on metamaterial

    International Nuclear Information System (INIS)

    Kim, Y J; Yoo, Y J; Hwang, J S; Lee, Y P

    2016-01-01

    We suggest that ultrathin broadband metamaterial is a perfect absorber in the microwave regime by utilizing the properties of a resistive sheet and metamaterial. Meta-atoms are composed of four-leaf clover-shape metallic patterns and a metal plane separated by three intermediate resistive sheet layers between four dielectric layers. We interpret the absorption mechanism of the broadband by using the distribution of surface currents at specific frequencies. The simulated absorption was over 99% in 1.8–4.2 GHz. The corresponding experimental absorption was also over 99% in 2.62–4.2 GHz; however, the absorption was slightly lower than 99% in 1.8–2.62 GHz because of the sheet resistance and the changed values for the dielectric constant. Furthermore, it is independent of incident angle. The results of this research indicate the possibility of applications, due to the suppression of noxious exposure, in cell phones, computers and microwave equipments. (paper)

  1. 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.

  2. Design and experimentally measure a high performance metamaterial filter

    Science.gov (United States)

    Xu, Ya-wen; Xu, Jing-cheng

    2018-03-01

    Metamaterial filter is a kind of expecting optoelectronic device. In this paper, a metal/dielectric/metal (M/D/M) structure metamaterial filter is simulated and measured. Simulated results indicate that the perfect impedance matching condition between the metamaterial filter and the free space leads to the transmission band. Measured results show that the proposed metamaterial filter achieves high performance transmission on TM and TE polarization directions. Moreover, the high transmission rate is also can be obtained when the incident angle reaches to 45°. Further measured results show that the transmission band can be expanded through optimizing structural parameters. The central frequency of the transmission band is also can be adjusted through optimizing structural parameters. The physical mechanism behind the central frequency shifted is solved through establishing an equivalent resonant circuit model.

  3. 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.

  4. 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.

  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. Substrate effects on terahertz metamaterial resonances for various metal thicknesses

    International Nuclear Information System (INIS)

    Park, S. J.; Ahn, Y. H.

    2014-01-01

    We demonstrate dielectric substrate effects on the resonance shift of terahertz metamaterials with various metal thicknesses by using finite-difference time-domain simulations. We found a small red shift in the metamaterial resonance with increasing metal thickness for the free-standing case. Conversely, when the metamaterial pattern was supported by a substrate with a high dielectric constant, the resonant frequency exhibited a large blue shift because the relative contribution of the substrate's refractive index to the resonant frequency decreased drastically as we increased the metal thickness. We determined the substrate's refractive index, 1.26, at which the metamaterial resonance was independent of the metal thickness. We extracted the effective refractive index as a function of the substrate's refractive index explicitly, which was noticeably different for different film thicknesses.

  7. 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 sh...

  8. 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...

  9. Monlinear fish-scale metamaterial via coupled duffing oscillators

    OpenAIRE

    Kochetov, Bogdan; Tuz, Vladimir; Mladyonov, Pavel; Prosvirnin, Sergey; Kochetova, Lyudmila

    2012-01-01

    The dynamic system of two coupled Duffing oscillators is considered in order to predict the optical response of the nonlinear planar fish-scale metamaterial. The direct numerical calculation of meta material response confirms the correctness of the proposed model

  10. 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.

  11. Preferential emission into epsilon-near-zero metamaterial [Invited

    International Nuclear Information System (INIS)

    Galfsky, Tal; Sun, Zheng; Jacob, Zubin; Menon, Vinod M.

    2015-01-01

    We report the use of epsilon near zero (ENZ) metamaterial to control spontaneous emission from Zinc-Oxide (ZnO) excitons. The ENZ material consists of alternating layers of silver and alumina with subwavelength thicknesses, resulting in an effective medium where one of the components of the dielectric constant approach zero between 370nm-440nm wavelength range. Bulk ZnO with photoluminescence maximum in the ENZ regime was deposited via atomic layer deposition to obtain a smooth film with near field coupling to the ENZ metamaterial. Preferential emission from the ZnO layer into the metamaterial with suppression of forward emission by 90% in comparison to ZnO on silicon is observed. We attribute this observation to the presence of dispersionless plasmonic modes in the ENZ regime as shown by the results of theoretical modeling presented here. Integration of ENZ metamaterials with light emitters is an attractive platform for realizing a low threshold subwavelength laser

  12. 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.

  13. Sound reduction by metamaterial-based acoustic enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Shanshan; Li, Pei; Zhou, Xiaoming; Hu, Gengkai, E-mail: hugeng@bit.edu.cn [Key Laboratory of Dynamics and Control of Flight Vehicle, Ministry of Education and School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China)

    2014-12-15

    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.

  14. 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...

  15. Fiber-Drawn Metamaterial for THz Waveguiding and Imaging

    DEFF Research Database (Denmark)

    Atakaramians, Shaghik; Stefani, Alessio; Li, Haisu

    2017-01-01

    and sub-diffraction imaging. We show the experimental demonstration of THz radiation guidance through hollow core waveguides with metamaterial cladding, where substantial improvements were realized compared to conventional hollow core waveguides, such as reduction of size, greater flexibility, increased...

  16. 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...

  17. 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.

  18. Scheme for achieving coherent perfect absorption by anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan; Wu, Ying

    2017-01-01

    in conjunction with retrieval method to determine practical metamaterial absorbers. The scheme is scalable to frequencies and applicable to various incident angles. Numerical simulations show that perfect absorption is achieved in the designed absorbers over a

  19. A review of nano-optics in metamaterial hybrid heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, Western University, London N6G 3K7 (Canada)

    2014-03-31

    We present a review for the nonlinear nano-optics in quantum dots doped in a metamaterial heterostructure. The heterostructure is formed by depositing a metamaterial on a dielectric substrate and ensemble of noninteracting quantum dots are doped near the heterostructure interface. It is shown that there is enhancement of the second harmonic generation due to the surface plasmon polaritons field present at the interface.

  20. 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.

  1. 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-...

  2. 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.

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

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Zalkovskij, Maksim

    2013-01-01

    response. In this presentation we overview our results on theory, fabrication and characterization of metal and graphene based metamaterials for the THz range. We show that the multiple layers of structured graphene can form a hyperbolic dispersion medium lens able to resolve the subwavelength features [2......]. We analyze the limitations and demonstrate numerically and experimentally the chiral and nonchiral thin-film metamaterial based polarization converters [3–5] and graphene total absorbers for THz radiation [6]....

  4. 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)

  5. 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....

  6. Sub-wavelength resonances in polygonal metamaterial cylinders

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Breinbjerg, Olav

    2008-01-01

    It has been shown that the sub-wavelength resonances of circular MTM cylinders also occur for polygonal MTM cylinders. This is the case for lossless and non-dispersive cylinders as well as lossy and dispersive cylinders. The sub-wavelength resonances are thus not limited to structures of canonical...

  7. Waves in man-made materials: superlattice to metamaterials

    Science.gov (United States)

    Tsu, Raphael; Fiddy, Michael A.

    2014-07-01

    While artificial or man-made structures date back to Lord Rayleigh, the work started by Lewin in 1947, placing spheres onto cubic lattices, greatly enriched microwave materials and devices. It was very suggestive of both metamaterials and photonics crystals. Effective medium models were used to describe bulk properties with some success. The concept of metamaterials followed photonic crystals, and these both were introduced after the introduction of the man-made superlattices designed to enrich the class of materials for electronic devices. The work on serrated ridged waveguides by Kirschbaum and Tsu for the control of the refractive index of microwave lenses as well as microwave matching devices in 1959 used a combination of theory, such as Floquet's theory, Bloch theory in one dimension, as well as periodic lumped loading. There is much in common between metamaterials and superlattices, but in this paper, we discuss some practical limitations to both. It is pointed out that unlike superlattices where kl > 1 is the most important criterion, metamaterials try to avoid involve such restrictions. However, the natural random fluctuations that limit the properties of naturally occurring materials are shown to take a toll on the theoretical predictions of metamaterials. The question is how great that toll, i.e. how significant those fluctuations will be, in diminishing the unusual properties that metamaterials can exhibit.

  8. Chiral metamaterials: from optical activity and negative refractive index to asymmetric transmission

    International Nuclear Information System (INIS)

    Li, Zhaofeng; Mutlu, Mehmet; Ozbay, Ekmel

    2013-01-01

    We summarize the progress in the development and application of chiral metamaterials. After a brief review of the salient features of chiral metamaterials, such as giant optical activity, circular dichroism, and negative refractive index, the common method for the retrieval of effective parameters for chiral metamaterials is surveyed. Then, we introduce some typical chiral structures, e.g., chiral metamaterial consisting of split ring resonators, complementary chiral metamaterial, and composite chiral metamaterial, on the basis of the studies of the authors’ group. The coupling effect during the construction of bulk chiral metamaterials is mentioned and discussed. We introduce the application of bianisotropic chiral structures in the field of asymmetric transmission. Finally, we mention a few directions for future research on chiral metamaterials. (review article)

  9. 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...

  10. 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.

  11. Structured Light-Matter Interactions Enabled By Novel Photonic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Litchinitser, Natalia [Univ. at Buffalo, NY (United States); Feng, Liang [Univ. at Buffalo, NY (United States)

    2017-05-02

    The synergy of complex materials and complex light is expected to add a new dimension to the science of light and its applications [1]. The goal of this program is to investigate novel phenomena emerging at the interface of these two branches of modern optics. While metamaterials research was largely focused on relatively “simple” linearly or circularly polarized light propagation in “complex” nanostructured, carefully designed materials with properties not found in nature, many singular optics studies addressed “complex” structured light transmission in “simple” homogeneous, isotropic, nondispersive transparent media, where both spin and orbital angular momentum are independently conserved. However, if both light and medium are complex so that structured light interacts with a metamaterial whose optical materials properties can be designed at will, the spin or angular momentum can change, which leads to spin-orbit interaction and many novel optical phenomena that will be studied in the proposed project. Indeed, metamaterials enable unprecedented control over light propagation, opening new avenues for using spin and quantum optical phenomena, and design flexibility facilitating new linear and nonlinear optical properties and functionalities, including negative index of refraction, magnetism at optical frequencies, giant optical activity, subwavelength imaging, cloaking, dispersion engineering, and unique phase-matching conditions for nonlinear optical interactions. In this research program we focused on structured light-matter interactions in complex media with three particularly remarkable properties that were enabled only with the emergence of metamaterials: extreme anisotropy, extreme material parameters, and magneto-electric coupling–bi-anisotropy and chirality.

  12. Photonics surface waves on metamaterials interfaces

    DEFF Research Database (Denmark)

    Takayama, Osamu; Bogdanov, Andrey; Lavrinenko, Andrei V

    2017-01-01

    A surface wave (SW) in optics is a light wave, which is supported at an interface of two dissimilar media and propagates along the interface with its field amplitude exponentially decaying away from the boundary. The research on surface waves has been flourishing in last few decades thanks...... to their unique properties of surface sensitivity and field localization. These features have resulted in applications in nano-guiding, sensing, light-trapping and imaging based on the near-field techniques, contributing to the establishment of the nanophotonics as a field of research. Up to present, a wide...... variety of surface waves has been investigated in numerous material and structure settings. This paper reviews the recent progress and development in the physics of SWs localized at metamaterial interfaces, as well as bulk media in order to provide broader perspectives on optical surface waves in general...

  13. 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.

  14. 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.

  15. Ultrasmooth Patterned Metals for Plasmonics and Metamaterials

    Science.gov (United States)

    Nagpal, Prashant; Lindquist, Nathan C.; Oh, Sang-Hyun; Norris, David J.

    2009-07-01

    Surface plasmons are electromagnetic waves that can exist at metal interfaces because of coupling between light and free electrons. Restricted to travel along the interface, these waves can be channeled, concentrated, or otherwise manipulated by surface patterning. However, because surface roughness and other inhomogeneities have so far limited surface-plasmon propagation in real plasmonic devices, simple high-throughput methods are needed to fabricate high-quality patterned metals. We combined template stripping with precisely patterned silicon substrates to obtain ultrasmooth pure metal films with grooves, bumps, pyramids, ridges, and holes. Measured surface-plasmon-propagation lengths on the resulting surfaces approach theoretical values for perfectly flat films. With the use of our method, we demonstrated structures that exhibit Raman scattering enhancements above 107 for sensing applications and multilayer films for optical metamaterials.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Terahertz polarization converter based on all-dielectric high birefringence metamaterial with elliptical air holes

    KAUST Repository

    Zi, Jianchen; Xu, Quan; Wang, Qiu; Tian, Chunxiu; Li, Yanfeng; Zhang, Xixiang; Han, Jiaguang; Zhang, Weili

    2018-01-01

    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

  1. A lossless multichannel bio-signal compression based on low-complexity joint coding scheme for portable medical devices.

    Science.gov (United States)

    Kim, Dong-Sun; Kwon, Jin-San

    2014-09-18

    Research on real-time health systems have received great attention during recent years and the needs of high-quality personal multichannel medical signal compression for personal medical product applications are increasing. The international MPEG-4 audio lossless coding (ALS) standard supports a joint channel-coding scheme for improving compression performance of multichannel signals and it is very efficient compression method for multi-channel biosignals. However, the computational complexity of such a multichannel coding scheme is significantly greater than that of other lossless audio encoders. In this paper, we present a multichannel hardware encoder based on a low-complexity joint-coding technique and shared multiplier scheme for portable devices. A joint-coding decision method and a reference channel selection scheme are modified for a low-complexity joint coder. The proposed joint coding decision method determines the optimized joint-coding operation based on the relationship between the cross correlation of residual signals and the compression ratio. The reference channel selection is designed to select a channel for the entropy coding of the joint coding. The hardware encoder operates at a 40 MHz clock frequency and supports two-channel parallel encoding for the multichannel monitoring system. Experimental results show that the compression ratio increases by 0.06%, whereas the computational complexity decreases by 20.72% compared to the MPEG-4 ALS reference software encoder. In addition, the compression ratio increases by about 11.92%, compared to the single channel based bio-signal lossless data compressor.

  2. Real-time lossless data compression techniques for long-pulse operation

    International Nuclear Information System (INIS)

    Jesus Vega, J.; Sanchez, E.; Portas, A.; Pereira, A.; Ruiz, M.

    2006-01-01

    Data logging and data distribution will be two main tasks connected with data handling in ITER. Data logging refers to the recovery and ultimate storage of all data, independent on the data source. Control data and physics data distribution is related, on the one hand, to the on-line data broadcasting for immediate data availability for both data analysis and data visualization. On the other hand, delayed analyses require off-line data access. Due to the large data volume expected, data compression will be mandatory in order to save storage and bandwidth. On-line data distribution in a long pulse environment requires the use of a deterministic approach to be able to ensure a proper response time for data availability. However, an essential feature for all the above purposes is to apply compression techniques that ensure the recovery of the initial signals without spectral distortion when compacted data are expanded (lossless techniques). Delta compression methods are independent on the analogue characteristics of waveforms and there exist a variety of implementations that have been applied to the databases of several fusion devices such as Alcator, JET and TJ-II among others. Delta compression techniques are carried out in a two step algorithm. The first step consists of a delta calculation, i.e. the computation of the differences between the digital codes of adjacent signal samples. The resultant deltas are then encoded according to constant- or variable-length bit allocation. Several encoding forms can be considered for the second step and they have to satisfy a prefix code property. However, and in order to meet the requirement of on-line data distribution, the encoding forms have to be defined prior to data capture. This article reviews different lossless data compression techniques based on delta compression. In addition, the concept of cyclic delta transformation is introduced. Furthermore, comparative results concerning compression rates on different

  3. Reflection and transmission of light at periodic layered metamaterial films

    Science.gov (United States)

    Paul, Thomas; Menzel, Christoph; Śmigaj, Wojciech; Rockstuhl, Carsten; Lalanne, Philippe; Lederer, Falk

    2011-09-01

    The appropriate description of light scattering (transmission/reflection) at a bulky artificial medium, consisting of a sequence of functional metamaterial and natural material films, represents a major challenge in current theoretical nano-optics. Because in many relevant cases, in particular, in the optical domain, a metamaterial must not be described by an effective permittivity and permeability the usual Fresnel formalism cannot be applied. A reliable alternative consists in using a Bloch mode formalism known, e.g., from the theory of photonic crystals. It permits to split this complex issue into two more elementary ones, namely the study of light propagation in an infinitely extended metamaterial and the analysis of light scattering at interfaces between adjacent meta and natural materials. The first problem is routinely solved by calculating the relevant Bloch modes and their dispersion relations. The second task is more involved and represents the subject of the present study. It consists in using the general Bloch mode orthogonality to derive rigorous expressions for the reflection and transmission coefficients at an interface between two three-dimensional absorptive periodic media for arbitrary incidence. A considerable simplification can be achieved if only the fundamental Bloch modes of both media govern the scattering properties at the interface. If this approximation is valid, which depends on the longitudinal metamaterial period, the periodic metamaterial may be termed homogeneous. Only in this case the disentanglement of the fundamental modes of both media can be performed and the reflection/transmission coefficients can be expressed in terms of two impedances, each depending solely on the properties of the fundamental mode of the respective medium. In order to complement the picture, we apply the present formalism to the quite general problem of reflection/transmission at a metamaterial film sandwiched between a dissimilar metamaterial. This

  4. Fabrication, Characterization, And Deformation of 3D Structural Meta-Materials

    Science.gov (United States)

    Montemayor, Lauren C.

    Current technological advances in fabrication methods have provided pathways to creating architected structural meta-materials similar to those found in natural organisms that are structurally robust and lightweight, such as diatoms. Structural meta-materials are materials with mechanical properties that are determined by material properties at various length scales, which range from the material microstructure (nm) to the macro-scale architecture (mum -- mm). It is now possible to exploit material size effect, which emerge at the nanometer length scale, as well as structural effects to tune the material properties and failure mechanisms of small-scale cellular solids, such as nanolattices. This work demonstrates the fabrication and mechanical properties of 3-dimensional hollow nanolattices in both tension and compression. Hollow gold nanolattices loaded in uniaxial compression demonstrate that strength and stiffness vary as a function of geometry and tube wall thickness. Structural effects were explored by increasing the unit cell angle from 30° to 60° while keeping all other parameters constant; material size effects were probed by varying the tube wall thickness, t, from 200nm to 635nm, at a constant relative density and grain size. In-situ uniaxial compression experiments reveal an order-of-magnitude increase in yield stress and modulus in nanolattices with greater lattice angles, and a 150% increase in the yield strength without a concomitant change in modulus in thicker-walled nanolattices for fixed lattice angles. These results imply that independent control of structural and material size effects enables tunability of mechanical properties of 3-dimensional architected meta-materials and highlight the importance of material, geometric, and microstructural effects in small-scale mechanics. This work also explores the flaw tolerance of 3D hollow-tube alumina kagome nanolattices with and without pre-fabricated notches, both in experiment and simulation

  5. Ultrathin triple-band polarization-insensitive wide-angle compact metamaterial absorber

    International Nuclear Information System (INIS)

    Shang, Shuai; Yang, Shizhong; Tao, Lu; Yang, Lisheng; Cao, Hailin

    2016-01-01

    In this study, the design, realization, and characterization of an ultrathin triple-band polarization-insensitive wide-angle metamaterial absorber are reported. The metamaterial absorber comprises a periodic array of modified six-fold symmetric snowflake-shaped resonators with strip spiral line load, which is printed on a dielectric substrate backed by a metal ground plane. It is shown that the absorber exhibits three distinct near-unity absorption peaks, which are distributed across C, X, Ku bands, respectively. Owing to the six-fold symmetry, the absorber is insensitive to the polarization of the incident radiation. In addition, the absorber shows excellent absorption performance over wide oblique incident angles for both transverse electric and transverse magnetic polarizations. Simulated surface current and field distributions at the three absorption peaks are demonstrated to understand the absorption mechanism. Particularly, the absorption modes come from the fundamental and high-order dipole resonances. Furthermore, the experimental verification of the designed absorber is conducted, and the measured results are in reasonable agreement with the simulated ones. The proposed ultrathin (∼0.018λ 0 , λ 0 corresponding to the lowest peak absorption frequency) compact (0.168λ 0 ×0.168λ 0 corresponding to the area of a unit cell) absorber enables potential applications such as stealth technology, electromagnetic interference and spectrum identification.

  6. Extreme control of light in metamaterials: Complete and loss-free stopping of light

    International Nuclear Information System (INIS)

    Tsakmakidis, Kosmas L.; Hess, Ortwin

    2012-01-01

    We present an overview of recent advances within the field of slow- and stopped-light in metamaterial and plasmonic waveguides. We start by elucidating the mechanisms by which these configurations can enable complete stopping of light. Decoherence mechanisms may destroy the zero-group-velocity condition for real-frequency/complex-wavevector modes, but we show that metamaterial and nanoplasmonic waveguides also support complex-frequency/real-wavevector modes that uphold the light-stopping condition. A further point of focus is how, by using gain, dissipative losses can be overcome in the slow- and stopped-light regimes. To this end, on the basis of full-wave finite-difference time-domain (FDTD) simulations and analytic transfer-matrix calculations, we show that the incorporation of thin layers made of an active medium, placed adjacently to the core layer of a negative-refractive-index waveguide, can fully remove dissipative losses - in a slow- or stopped-light regime where the effective index of the guided lightwave remains negative.

  7. Anisotropic metamaterial for efficiency enhancement of mid-range wireless power transfer under coil misalignment

    International Nuclear Information System (INIS)

    Ranaweera, A L A K; Moscoso, Carlos Arriola; Lee, Jong-Wook

    2015-01-01

    In a wireless power transfer (WPT) system, misalignment between transmitter and receiver coils is one of the key factors affecting efficiency. Recently, metamaterials have shown great potential to enhance electromagnetic propagation in various environments. In this work, we apply a metamaterial to enhance the WPT in a more general environment where misalignment is considered. Using an anisotropic metamaterial, we obtain a significant efficiency enhancement. Therefore, we propose that the metamaterial is an effective means to mitigate the decreased efficiency caused by misalignment. In addition, we investigate the effect of coil misalignment on the threshold distance beyond which the metamaterial enhances the performance of WPT. (paper)

  8. 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....

  9. JPEG XS, a new standard for visually lossless low-latency lightweight image compression

    Science.gov (United States)

    Descampe, Antonin; Keinert, Joachim; Richter, Thomas; Fößel, Siegfried; Rouvroy, Gaël.

    2017-09-01

    JPEG XS is an upcoming standard from the JPEG Committee (formally known as ISO/IEC SC29 WG1). It aims to provide an interoperable visually lossless low-latency lightweight codec for a wide range of applications including mezzanine compression in broadcast and Pro-AV markets. This requires optimal support of a wide range of implementation technologies such as FPGAs, CPUs and GPUs. Targeted use cases are professional video links, IP transport, Ethernet transport, real-time video storage, video memory buffers, and omnidirectional video capture and rendering. In addition to the evaluation of the visual transparency of the selected technologies, a detailed analysis of the hardware and software complexity as well as the latency has been done to make sure that the new codec meets the requirements of the above-mentioned use cases. In particular, the end-to-end latency has been constrained to a maximum of 32 lines. Concerning the hardware complexity, neither encoder nor decoder should require more than 50% of an FPGA similar to Xilinx Artix 7 or 25% of an FPGA similar to Altera Cyclon 5. This process resulted in a coding scheme made of an optional color transform, a wavelet transform, the entropy coding of the highest magnitude level of groups of coefficients, and the raw inclusion of the truncated wavelet coefficients. This paper presents the details and status of the standardization process, a technical description of the future standard, and the latest performance evaluation results.

  10. An Edge-Sensing Predictor in Wavelet Lifting Structures for Lossless Image Coding

    Directory of Open Access Journals (Sweden)

    Ömer N. Gerek

    2007-02-01

    Full Text Available The introduction of lifting implementations for image wavelet decomposition generated possibilities of several applications and several adaptive decomposition variations. The prediction step of a lifting stage constitutes the interesting part of the decomposition since it aims to reduce the energy of one of the decomposition bands by making predictions using the other decomposition band. In that aspect, more successful predictions yield better efficiency in terms of reduced energy in the lower band. In this work, we present a prediction filter whose prediction domain pixels are selected adaptively according to the local edge characteristics of the image. By judicuously selecting the prediction domain from pixels that are expected to have closer relation to the estimated pixel, the prediction error signal energy is reduced. In order to keep the adaptation rule symmetric for the encoder and the decoder sides, lossless compression applications are examined. Experimental results show that the proposed algorithm provides good compression results. Furthermore, the edge calculation is computationally inexpensive and comparable to the famous Daubechies 5/3 lifting implementation.

  11. A high-speed lossless data compression system for space applications

    Science.gov (United States)

    Miko, Joe; Fong, Wai; Miller, Warner

    1993-01-01

    This paper reports on the integration of a lossless data compression/decompression chipset into a space data system architecture. For its compression engine, the data system incorporates the Universal Source Encoder (USE) designed for the NASA/Goddard Space Flight Center. Currently, the data compression testbed generates video frames consisting of 512 lines of 512 pixels having 8-bit resolution. Each image is passed through the USE where the lines are internally partitioned into 16-word blocks. These blocks are adaptively encoded across widely varying entropy levels using a Rice 12-option set coding algorithm. The current system operates at an Input/Output rate of 10 Msamples/s or 80 Mbits/s for each buffered input line. Frame and line synchronization for each image are maintained through the use of uniquely decodable command words. Length information of each variable length compressed image line is also included in the output stream. The data and command information are passed to the next stage of the system architecture through a serial fiber-optic transmitter. The initial segment of this stage consists of packetizer hardware which adds an appropriate CCSDS header to the received source data. An uncompressed mode is optionally available to pass image lines directly to the packetizer hardware. A data decompression testbed has also been developed to confirm the data compression operation.

  12. A Hybrid Constant and Oscillatory Field Ion Mobility Analyzer Using Structures for Lossless Ion Manipulations

    Science.gov (United States)

    Prabhakaran, Aneesh; Hamid, Ahmed M.; Garimella, Sandilya V. B.; Valenzuela, Blandina R.; Ewing, Robert G.; Ibrahim, Yehia M.; Smith, Richard D.

    2018-02-01

    Here we explore the combination of constant and oscillatory fields applied in a single device to affect the continuous separation and filtering of ions based on their mobilities. The device explored allows confining and manipulating ions utilizing a combination of radio frequency (rf), direct current (DC) fields, and traveling waves (TW) in a structures for lossless ion manipulations (SLIM) module. We have investigated theoretically and experimentally a concept for continuous filtering of ions based on their mobilities where ions are mobility separated and selected by passage through two regions, both of which incorporated combined TW and constant fields providing opposing forces on the ions. The SLIM module was composed of two surfaces with mirror-image arrays of electrodes and had two regions where the different TW and opposing DC fields could be applied. The filtering capabilities are determined by the applied DC gradient and the TW parameters, such as speed, amplitude, and the TW sequence (i.e., the duty cycle of the traveling wave). The effects of different parameters on the sensitivity and the ion mobility (IM) resolution of the device have been investigated. By appropriately choosing the DC gradient and TW parameters for the two sections, it is possible to transmit ions of a selected mobility while filtering out others of both higher and lower mobility. The novel device described here provides a basis for the targeted analysis of compounds based upon the continuous selection of ions according to their mobility and without the need for high electric fields or pulsed injection.

  13. Near-lossless multichannel EEG compression based on matrix and tensor decompositions.

    Science.gov (United States)

    Dauwels, Justin; Srinivasan, K; Reddy, M Ramasubba; Cichocki, Andrzej

    2013-05-01

    A novel near-lossless compression algorithm for multichannel electroencephalogram (MC-EEG) is proposed based on matrix/tensor decomposition models. MC-EEG is represented in suitable multiway (multidimensional) forms to efficiently exploit temporal and spatial correlations simultaneously. Several matrix/tensor decomposition models are analyzed in view of efficient decorrelation of the multiway forms of MC-EEG. A compression algorithm is built based on the principle of “lossy plus residual coding,” consisting of a matrix/tensor decomposition-based coder in the lossy layer followed by arithmetic coding in the residual layer. This approach guarantees a specifiable maximum absolute error between original and reconstructed signals. The compression algorithm is applied to three different scalp EEG datasets and an intracranial EEG dataset, each with different sampling rate and resolution. The proposed algorithm achieves attractive compression ratios compared to compressing individual channels separately. For similar compression ratios, the proposed algorithm achieves nearly fivefold lower average error compared to a similar wavelet-based volumetric MC-EEG compression algorithm.

  14. Freeing Space for NASA: Incorporating a Lossless Compression Algorithm into NASA's FOSS System

    Science.gov (United States)

    Fiechtner, Kaitlyn; Parker, Allen

    2011-01-01

    NASA's Fiber Optic Strain Sensing (FOSS) system can gather and store up to 1,536,000 bytes (1.46 megabytes) per second. Since the FOSS system typically acquires hours - or even days - of data, the system can gather hundreds of gigabytes of data for a given test event. To store such large quantities of data more effectively, NASA is modifying a Lempel-Ziv-Oberhumer (LZO) lossless data compression program to compress data as it is being acquired in real time. After proving that the algorithm is capable of compressing the data from the FOSS system, the LZO program will be modified and incorporated into the FOSS system. Implementing an LZO compression algorithm will instantly free up memory space without compromising any data obtained. With the availability of memory space, the FOSS system can be used more efficiently on test specimens, such as Unmanned Aerial Vehicles (UAVs) that can be in flight for days. By integrating the compression algorithm, the FOSS system can continue gathering data, even on longer flights.

  15. Assembling optically active and nonactive metamaterials with chiral units

    Directory of Open Access Journals (Sweden)

    Xiang Xiong

    2012-12-01

    Full Text Available Metamaterials constructed with chiral units can be either optically active or nonactive depending on the spatial configuration of the building blocks. For a class of chiral units, their effective induced electric and magnetic dipoles, which originate from the induced surface electric current upon illumination of incident light, can be collinear at the resonant frequency. This feature provides significant advantage in designing metamaterials. In this paper we concentrate on several examples. In one scenario, chiral units with opposite chiralities are used to construct the optically nonactive metamaterial structure. It turns out that with linearly polarized incident light, the pure electric or magnetic resonance (and accordingly negative permittivity or negative permeability can be selectively realized by tuning the polarization of incident light for 90°. Alternatively, units with the same chirality can be assembled as a chiral metamaterial by taking the advantage of the collinear induced electric and magnetic dipoles. It follows that for the circularly polarized incident light, negative refractive index can be realized. These examples demonstrate the unique approach to achieve certain optical properties by assembling chiral building blocks, which could be enlightening in designing metamaterials.

  16. 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.

  17. 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.

  18. Ultra-thin infrared metamaterial detector for multicolor imaging applications.

    Science.gov (United States)

    Montoya, John A; Tian, Zhao-Bing; Krishna, Sanjay; Padilla, Willie J

    2017-09-18

    The next generation of infrared imaging systems requires control of fundamental electromagnetic processes - absorption, polarization, spectral bandwidth - at the pixel level to acquire desirable information about the environment with low system latency. Metamaterial absorbers have sparked interest in the infrared imaging community for their ability to enhance absorption of incoming radiation with color, polarization and/or phase information. However, most metamaterial-based sensors fail to focus incoming radiation into the active region of a ultra-thin detecting element, thus achieving poor detection metrics. Here our multifunctional metamaterial absorber is directly integrated with a novel mid-wave infrared (MWIR) and long-wave infrared (LWIR) detector with an ultra-thin (~λ/15) InAs/GaSb Type-II superlattice (T2SL) interband cascade detector. The deep sub-wavelength metamaterial detector architecture proposed and demonstrated here, thus significantly improves the detection quantum efficiency (QE) and absorption of incoming radiation in a regime typically dominated by Fabry-Perot etalons. Our work evinces the ability of multifunctional metamaterials to realize efficient wavelength selective detection across the infrared spectrum for enhanced multispectral infrared imaging applications.

  19. Seismic isolation of buildings using composite foundations based on metamaterials

    Science.gov (United States)

    Casablanca, O.; Ventura, G.; Garescı, F.; Azzerboni, B.; Chiaia, B.; Chiappini, M.; Finocchio, G.

    2018-05-01

    Metamaterials can be engineered to interact with waves in entirely new ways, finding application on the nanoscale in various fields such as optics and acoustics. In addition, acoustic metamaterials can be used in large-scale experiments for filtering and manipulating seismic waves (seismic metamaterials). Here, we propose seismic isolation based on a device that combines some properties of seismic metamaterials (e.g., periodic mass-in-mass systems) with that of a standard foundation positioned right below the building for isolation purposes. The concepts on which this solution is based are the local resonance and a dual-stiffness structure that preserves large (small) rigidity for compression (shear) effects. In other words, this paper introduces a different approach to seismic isolation by using certain principles of seismic metamaterials. The experimental demonstrator tested on the laboratory scale exhibits a spectral bandgap that begins at 4.5 Hz. Within the bandgap, it filters more than 50% of the seismic energy via an internal dissipation process. Our results open a path toward the seismic resilience of buildings and a critical infrastructure to shear seismic waves, achieving higher efficiency compared to traditional seismic insulators and passive energy-dissipation systems.

  20. Tunable bandgaps in a deployable metamaterial

    Science.gov (United States)

    Nanda, Aditya; Karami, M. A.

    2018-06-01

    In this manuscript, we investigate deployable structures (such as solar arrays) and origami-inspired foldable structures as metamaterials capable of tunable wave manipulation. Specifically, we present a metamaterial whose bandgaps can be modulated by changing the fold angle of adjacent panels. The repeating unit cell of the structure consists of a beam (representing a panel) and a torsional spring (representing the folding mechanism). Two important cases are considered. Firstly, the fold angle (angle between adjacent beams), Ψ, is zero and only flexural waves propagate. In the second case, the fold angle is greater than zero (Ψ > 0). This causes longitudinal and transverse vibration to be coupled. FEM models are used to validate both these analyses. Increasing the fold angle was found to inflict notable changes to the wave transmission characteristics of the structure. In general, increasing the fold angles caused the bandwidth of bandgaps to increase. For the lowest four bandgaps we found bandwidth increases of 252 %, 177 %, 230 % and 163 % respectively at Ψ = 90 deg (relative to the bandwidths at Ψ = 0). In addition, non-trivial increases in bandwidth of the odd-numbered bandgaps occurs even at small fold angles-the bandwidth for the first and third bandgaps effectively double in size (increase by 100 %) at Ψ = 20 deg relative to those at Ψ = 0. This could have ramifications in the context of tunable wave manipulation and adaptive filtering. In addition, by expanding out the characteristic equation of transfer matrix for the straight structure, we prove that the upper band edge of the nth bandgap will always equal the nth simply supported natural frequency of the constituent beam. Further, we found that the ratio (EI/kt) is a pertinent parameter affecting the bandwidth of bandgaps. For low values of the ratio, effectively, no bandgap exists. For higher values of the ratio (EI/kt), we obtain a relatively large bandgap over which no waves propagate. This can

  1. Anomalously Weak Scattering in Metal-Semiconductor Multilayer Hyperbolic Metamaterials

    Directory of Open Access Journals (Sweden)

    Hao Shen

    2015-05-01

    Full Text Available In contrast to strong plasmonic scattering from metal particles or structures in metal films, we show that patterns of arbitrary shape fabricated out of multilayer hyperbolic metamaterials become invisible within a chosen band of optical frequencies. This is due to anomalously weak scattering when the in-plane permittivity of the multilayer hyperbolic metamaterials is tuned to match with the surrounding medium. This new phenomenon is described theoretically and demonstrated experimentally by optical characterization of various patterns in Au-Si multilayer hyperbolic metamaterials. This anomalously weak scattering is insensitive to pattern sizes, shapes, and incident angles, and has potential applications in scattering cross-section engineering, optical encryption, low-observable conductive probes, and optoelectric devices.

  2. Textile inspired flexible metamaterial with negative refractive index

    Science.gov (United States)

    Burgnies, L.; Lheurette, É.; Lippens, D.

    2015-04-01

    This work introduces metallo-dielectric woven fabric as a metamaterial for phase-front manipulation. Dispersion diagram as well as effective medium parameters retrieved from reflection and transmission coefficients point out negative values of refractive index. By numerical simulations, it is evidenced that a pair of meandered metallic wires, arranged in a top to bottom configuration, can yield to a textile metamaterial with simultaneously negative permittivity and permeability. While the effective negative permittivity stems from the metallic grid arrangement, resonating current loop resulting from the top to bottom configuration of two meandered metallic wires in near proximity produces magnetic activity with negative permeability. By adjusting the distance between pairs of metallic wires, the electric plasma frequency can be shifted to overlap the magnetic resonance. Finally, it is shown that the woven metamaterial is insensitive to the incident angle up to around 60°.

  3. Forced underwater laminar flows with active magnetohydrodynamic metamaterials

    Science.gov (United States)

    Culver, Dean; Urzhumov, Yaroslav

    2017-12-01

    Theory and practical implementations for wake-free propulsion systems are proposed and proven with computational fluid dynamic modeling. Introduced earlier, the concept of active hydrodynamic metamaterials is advanced by introducing magnetohydrodynamic metamaterials, structures with custom-designed volumetric distribution of Lorentz forces acting on a conducting fluid. Distributions of volume forces leading to wake-free, laminar flows are designed using multivariate optimization. Theoretical indications are presented that such flows can be sustained at arbitrarily high Reynolds numbers. Moreover, it is shown that in the limit Re ≫102 , a fixed volume force distribution may lead to a forced laminar flow across a wide range of Re numbers, without the need to reconfigure the force-generating metamaterial. Power requirements for such a device are studied as a function of the fluid conductivity. Implications to the design of distributed propulsion systems underwater and in space are discussed.

  4. Regression Methods for Ophthalmic Glucose Sensing Using Metamaterials

    Directory of Open Access Journals (Sweden)

    Philipp Rapp

    2011-01-01

    Full Text Available We present a novel concept for in vivo sensing of glucose using metamaterials in combination with automatic learning systems. In detail, we use the plasmonic analogue of electromagnetically induced transparency (EIT as sensor and evaluate the acquired data with support vector machines. The metamaterial can be integrated into a contact lens. This sensor changes its optical properties such as reflectivity upon the ambient glucose concentration, which allows for in situ measurements in the eye. We demonstrate that estimation errors below 2% at physiological concentrations are possible using simulations of the optical properties of the metamaterial in combination with an appropriate electrical circuitry and signal processing scheme. In the future, functionalization of our sensor with hydrogel will allow for a glucose-specific detection which is insensitive to other tear liquid substances providing both excellent selectivity and sensitivity.

  5. Quantum metamaterials in the microwave and optical ranges

    Energy Technology Data Exchange (ETDEWEB)

    Zagoskin, Alexandre M. [Loughborough University, Department of Physics, Loughborough (United Kingdom); Moscow Institute for Steel and Alloys, Theoretical Physics and Quantum Technologies Department, Moscow (Russian Federation); Felbacq, Didier; Rousseau, Emmanuel [University of Montpellier, Laboratory Charles Coulomb UMR CNRS-UM 5221, Montpellier (France)

    2016-12-15

    Quantum metamaterials generalize the concept of metamaterials (artificial optical media) to the case when their optical properties are determined by the interplay of quantum effects in the constituent 'artificial atoms' with the electromagnetic field modes in the system. The theoretical investigation of these structures demonstrated that a number of new effects (such as quantum birefringence, strongly nonclassical states of light, etc.) are to be expected, prompting the efforts on their fabrication and experimental investigation. Here we provide a summary of the principal features of quantum metamaterials and review the current state of research in this quickly developing field, which bridges quantum optics, quantum condensed matter theory and quantum information processing. (orig.)

  6. Gradient index metamaterials realized by drilling hole arrays

    International Nuclear Information System (INIS)

    Mei Zhonglei; Cui Tiejun; Bai Jing

    2010-01-01

    Gradient index metamaterials have wide applications in the microwave and optical fields. Based on the quasi-static theory, such materials at the microwave band have been realized by drilling hole arrays on ordinary dielectric materials. As applications of the gradient index metamaterials, novel devices including a 45 0 dielectric wave-bending structure, a 16 0 wave-steering lens and a microwave focusing lens are designed and fabricated. Field mapping measurements validate the proposed gradient index metamaterials and the device designs. The method can be directly and easily extended to the design of cloaks, various lenses, beam shifters and beam-steering devices. It can also be applied in the optical band as long as quasi-static conditions are satisfied. The method and the devices may find applications in integrated circuit systems.

  7. An effective medium description of 'Swiss Rolls', a magnetic metamaterial

    International Nuclear Information System (INIS)

    Wiltshire, M C K; Pendry, J B; Williams, W; Hajnal, J V

    2007-01-01

    The 'Swiss Roll' metamaterial medium is well suited to operation in the radio frequency (RF) range, because it has a low resonant frequency and a strong magnetic response. Two prisms of this material, one hexagonal and one square, have been constructed and characterized both at the metamaterial's resonant frequency of 21.5 MHz and above it, where the effective permeability is strongly negative. A series of spatial resonances is observed in the field patterns on the surfaces of the prisms. Using an effective medium description, we have carried out both analytical and numerical modelling of the electromagnetic behaviour of the metamaterial, and find, within certain obvious limitations, extremely good agreement between the measured and modelled results

  8. Performance of terahertz metamaterials as high-sensitivity sensor

    Science.gov (United States)

    He, Yanan; Zhang, Bo; Shen, Jingling

    2017-09-01

    A high-sensitivity sensor based on the resonant transmission characteristics of terahertz (THz) metamaterials was investigated, with the proposal and fabrication of rectangular bar arrays of THz metamaterials exhibiting a period of 180 μm on a 25 μm thick flexible polyimide. Varying the size of the metamaterial structure revealed that the length of the rectangular unit modulated the resonant frequency, which was verified by both experiment and simulation. The sensing characteristics upon varying the surrounding media in the sample were tested by simulation and experiment. Changing the surrounding medium from that of air to that of alcohol or oil produced resonant frequency redshifts of 80 GHz or 150 GHz, respectively, which indicates that the sensor possessed a high sensitivity of 667 GHz per unit of refractive index. Finally, the influence of the sample substrate thickness on the sensor sensitivity was investigated by simulation. It may be a reference for future sensor design.

  9. Metamaterial based embedded acoustic filters for structural applications

    Directory of Open Access Journals (Sweden)

    Hongfei Zhu

    2013-09-01

    Full Text Available We investigate the use of acoustic metamaterials to design structural materials with frequency selective characteristics. By exploiting the properties of acoustic metamaterials, we tailor the propagation characteristics of the host structure to effectively filter the constitutive harmonics of an incoming broadband excitation. The design approach exploits the characteristics of acoustic waveguides coupled by cavity modes. By properly designing the cavity we can tune the corresponding resonant mode and, therefore, coupling the waveguide at a prescribed frequency. This structural design can open new directions to develop broadband passive vibrations and noise control systems fully integrated in structural components.

  10. Dual band metamaterial perfect absorber based on Mie resonances

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; 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); Bi, Ke [School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Zhao, Qian [State Key Lab of Tribology, Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084 (China)

    2016-08-08

    We numerically and experimentally demonstrated a polarization insensitive dual-band metamaterial perfect absorber working in wide incident angles based on the two magnetic Mie resonances of a single dielectric “atom” with simple structure. Two absorption bands with simulated absorptivity of 99% and 96%, experimental absorptivity of 97% and 94% at 8.45 and 11.97 GHz were achieved due to the simultaneous magnetic and electric resonances in dielectric “atom” and copper plate. Mie resonances of dielectric “atom” provide a simple way to design metamaterial perfect absorbers with high symmetry.

  11. Scheme for achieving coherent perfect absorption by anisotropic metamaterials

    KAUST Repository

    Zhang, Xiujuan

    2017-02-22

    We propose a unified scheme to achieve coherent perfect absorption of electromagnetic waves by anisotropic metamaterials. The scheme describes the condition on perfect absorption and offers an inverse design route based on effective medium theory in conjunction with retrieval method to determine practical metamaterial absorbers. The scheme is scalable to frequencies and applicable to various incident angles. Numerical simulations show that perfect absorption is achieved in the designed absorbers over a wide range of incident angles, verifying the scheme. By integrating these absorbers, we further propose an absorber to absorb energy from two coherent point sources.

  12. Tunable waveguide bends with graphene-based anisotropic metamaterials

    KAUST Repository

    Chen, Zhao-xian; Chen, Ze-guo; Ming, Yang; Wu, Ying; Lu, Yan-qing

    2016-01-01

    We design tunable waveguide bends filled with graphene-based anisotropic metamaterials to achieve a nearly perfect bending effect. The anisotropic properties of the metamaterials can be described by the effective medium theory. The nearly perfect bending effect is demonstrated by finite element simulations of various structures with different bending curvatures and shapes. This effect is attributed to zero effective permittivity along the direction of propagation and matched effective impedance at the interfaces between the bending part and the dielectric waveguides. We envisage that the design will be applicable in the far-infrared and terahertz frequency ranges owing to the tunable dielectric responses of graphene.

  13. Experimental demonstration of superconducting critical temperature increase in electromagnetic metamaterials.

    Science.gov (United States)

    Smolyaninova, Vera N; Yost, Bradley; Zander, Kathryn; Osofsky, M S; Kim, Heungsoo; Saha, Shanta; Greene, R L; Smolyaninov, Igor I

    2014-12-04

    A recent proposal that the metamaterial approach to dielectric response engineering may increase the critical temperature of a composite superconductor-dielectric metamaterial has been tested in experiments with compressed mixtures of tin and barium titanate nanoparticles of varying composition. An increase of the critical temperature of the order of ΔT ~ 0.15 K compared to bulk tin has been observed for 40% volume fraction of barium titanate nanoparticles. Similar results were also obtained with compressed mixtures of tin and strontium titanate nanoparticles.

  14. Experimental demonstration of superconducting critical temperature increase in electromagnetic metamaterials

    Science.gov (United States)

    Smolyaninova, Vera N.; Yost, Bradley; Zander, Kathryn; Osofsky, M. S.; Kim, Heungsoo; Saha, Shanta; Greene, R. L.; Smolyaninov, Igor I.

    2014-12-01

    A recent proposal that the metamaterial approach to dielectric response engineering may increase the critical temperature of a composite superconductor-dielectric metamaterial has been tested in experiments with compressed mixtures of tin and barium titanate nanoparticles of varying composition. An increase of the critical temperature of the order of ΔT ~ 0.15 K compared to bulk tin has been observed for 40% volume fraction of barium titanate nanoparticles. Similar results were also obtained with compressed mixtures of tin and strontium titanate nanoparticles.

  15. Anisotropic mass density by two-dimensional acoustic metamaterials

    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 s/n, E-46022 Valencia (Spain)], E-mail: jsdehesa@upvnet.upv.es

    2008-02-15

    We show that specially designed two-dimensional arrangements of full elastic cylinders embedded in a nonviscous fluid or gas define (in the homogenization limit) a new class of acoustic metamaterials characterized by a dynamical effective mass density that is anisotropic. Here, analytic expressions for the dynamical mass density and the effective sound velocity tensors are derived in the long wavelength limit. Both show an explicit dependence on the lattice filling fraction, the elastic properties of cylinders relative to the background, their positions in the unit cell, and their multiple scattering interactions. Several examples of these metamaterials are reported and discussed.

  16. Tunable waveguide bends with graphene-based anisotropic metamaterials

    KAUST Repository

    Chen, Zhao-xian

    2016-01-15

    We design tunable waveguide bends filled with graphene-based anisotropic metamaterials to achieve a nearly perfect bending effect. The anisotropic properties of the metamaterials can be described by the effective medium theory. The nearly perfect bending effect is demonstrated by finite element simulations of various structures with different bending curvatures and shapes. This effect is attributed to zero effective permittivity along the direction of propagation and matched effective impedance at the interfaces between the bending part and the dielectric waveguides. We envisage that the design will be applicable in the far-infrared and terahertz frequency ranges owing to the tunable dielectric responses of graphene.

  17. Electromagnetically Induced Transparency in Symmetric Planar Metamaterial at THz Wavelengths

    Directory of Open Access Journals (Sweden)

    Abdelwaheb Ourir

    2015-03-01

    Full Text Available We report the experimental observation and the evidence of the analogue of electromagnetically-induced transparency (EIT in a symmetric planar metamaterial. This effect has been obtained in the THz range thanks to a destructive Fano-interference between the two first modes of an array of multi-gap split ring resonators deposited on a silicon substrate. This structure is a planar thin film material with four-fold symmetry. Thanks to this property, a polarization-independent transmission has been achieved. The proposed metamaterial is well adapted to variety of slow-light applications in the infrared and optical range.

  18. Looking into meta-atoms of plasmonic nanowire metamaterial

    KAUST Repository

    Tsai, Kuntong

    2014-09-10

    Nanowire-based plasmonic metamaterials exhibit many intriguing properties related to the hyperbolic dispersion, negative refraction, epsilon-near-zero behavior, strong Purcell effect, and nonlinearities. We have experimentally and numerically studied the electromagnetic modes of individual nanowires (meta-atoms) forming the metamaterial. High-resolution, scattering-type near-field optical microscopy has been used to visualize the intensity and phase of the modes. Numerical and analytical modeling of the mode structure is in agreement with the experimental observations and indicates the presence of the nonlocal response associated with cylindrical surface plasmons of nanowires.

  19. Babinet principle applied to the design of metasurfaces and metamaterials.

    Science.gov (United States)

    Falcone, F; Lopetegi, T; Laso, M A G; Baena, J D; Bonache, J; Beruete, M; Marqués, R; Martín, F; Sorolla, M

    2004-11-05

    The electromagnetic theory of diffraction and the Babinet principle are applied to the design of artificial metasurfaces and metamaterials. A new particle, the complementary split rings resonator, is proposed for the design of metasurfaces with high frequency selectivity and planar metamaterials with a negative dielectric permittivity. Applications in the fields of frequency selective surfaces and polarizers, as well as in microwave antennas and filter design, can be envisaged. The tunability of all these devices by an applied dc voltage is also achievable if these particles are etched on the appropriate substrate.

  20. Hazardous materials sensing: An electrical metamaterial approach

    Energy Technology Data Exchange (ETDEWEB)

    Rawat, Vaishali; Kitture, Rohini [Department of Applied Physics, Defence Institute of Advanced Technology (DIAT), Girinagar, Pune 411025 (India); Kumari, Dimple [Department of Applied Chemistry, Defence Institute of Advanced Technology (DIAT), Girinagar, Pune 411025 (India); Rajesh, Harsh [Society for Applied Microwave Electronics Engineering and Research (SAMEER), IIT-Bombay Campus, Powai, Mumbai (India); Banerjee, Shaibal [Department of Applied Chemistry, Defence Institute of Advanced Technology (DIAT), Girinagar, Pune 411025 (India); Kale, S.N., E-mail: sangeetakale2004@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology (DIAT), Girinagar, Pune 411025 (India)

    2016-10-01

    Metamaterials are recently emerging materials exhibiting amazing properties such as extremely miniaturized antennas, waveguides, optical couplers, multiplexers and filters. Such structures also respond to the variation in their ambient conditions when exposed to toxic and hazardous materials, which are especially hazardous to human health. Through this manuscript, we document our studies on three different high energy materials; namely 2- bromo-2nitropropane-1,3-diol (BNP), bis (1,3-diazido prop-2-yl) malonate (AM) and bis (1,3-diazido prop-2-yl) glutarate (AG). A Complementary Split Ring Resonator has been fabricated at resonant frequency of 4.48 GHz using copper on FR4 substrate. The energetic materials were exposed to the sensor and results were monitored using Vector Network Analyzer. The volume of liquids was varied from 0.5 µL to 3 µL. Prominent and explicit shifts in the transmission resonant frequency and amplitude was seen as a signature of each energetic material. The signatures were not only sensitive to the specific toxic group in the material but also to the volume of the liquid subjected to this sensor. The results are correlated with the simulation results, basic chemistry of the materials and permittivity measurements. The ultra-fast reversibility and repeatability, with good sensitivity and specificity of these devices project their applications in sensitive locations, particularly to combat for human security and health issues.

  1. Controlling enhanced absorption in graphene metamaterial

    Science.gov (United States)

    Zhou, Qihui; Liu, Peiguo; Bian, Li-an; Liu, Hanqing; Liu, Chenxi; Chen, Genghui

    2018-04-01

    In this paper, a controllable terahertz (THz) metamaterial absorber (MA) is designed with the circuit analog method. Taking advantage of the patterned graphene on SiO2/doped Si/polyimide substrates with a gold reflector, the controllable MA achieves perfect absorption at 0.75 THz. The chemical potential of graphene is regulated by controlling the voltage between graphene and doped Si layers. As the chemical potential varies from 0 eV to 0.5 eV, the MA is changed from reflection (0.99). The distributions of surface current and electric field are illustrated to analyze the resonant characteristic of patterned graphene. According to the resonant characteristic, we introduce patterned graphene elements with different dimension in a unit cell, which effectively extends the effective absorption bandwidth (absorption > 0 . 9) from 0.67-0.93 THz to 0.52-0.95 THz. Moreover, replacing part of the graphene structure with gold, the switchable MA is turned into a frequency tunable MA. The absorption peak moves from 0.62 THz to 0.92 THz as the chemical potential increases from 0.1 eV to 0.5 eV. These designs overcome limitation of traditional absorbers and exhibit great potentials in many practical applications.

  2. Photonics surface waves on metamaterials interfaces.

    Science.gov (United States)

    Takayama, Osamu; Bogdanov, Andrey; Lavrinenko, Andrei V

    2017-09-12

    A surface wave (SW) in optics is a light wave, which is supported at an interface of two dissimilar media and propagates along the interface with its field amplitude exponentially decaying away from the boundary. The research on surface waves has been flourishing in last few decades thanks to their unique properties of surface sensitivity and field localization. These features have resulted in applications in nano-guiding, sensing, light-trapping and imaging based on the near-field techniques, contributing to the establishment of the nanophotonics as a field of research. Up to present, a wide variety of surface waves has been investigated in numerous material and structure settings. This paper reviews the recent progress and development in the physics of SWs localized at metamaterial interfaces, as well as bulk media in order to provide broader perspectives on optical surface waves in general. For each type of the surface waves, we discuss material and structural platforms. We mainly focus on experimental realizations in the visible and near-infrared wavelength ranges. We also address existing and potential application of SWs in chemical and biological sensing, and experimental excitation and characterization methods. © 2017 IOP Publishing Ltd.

  3. Static non-reciprocity in mechanical metamaterials.

    Science.gov (United States)

    Coulais, Corentin; Sounas, Dimitrios; Alù, Andrea

    2017-02-23

    Reciprocity is a general, fundamental principle governing various physical systems, which ensures that the transfer function-the transmission of a physical quantity, say light intensity-between any two points in space is identical, regardless of geometrical or material asymmetries. Breaking this transmission symmetry offers enhanced control over signal transport, isolation and source protection. So far, devices that break reciprocity (and therefore show non-reciprocity) have been mostly considered in dynamic systems involving electromagnetic, acoustic and mechanical wave propagation associated with fields varying in space and time. Here we show that it is possible to break reciprocity in static systems, realizing mechanical metamaterials that exhibit vastly different output displacements under excitation from different sides, as well as one-way displacement amplification. This is achieved by combining large nonlinearities with suitable geometrical asymmetries and/or topological features. In addition to extending non-reciprocity and isolation to statics, our work sheds light on energy propagation in nonlinear materials with asymmetric crystalline structures and topological properties. We anticipate that breaking reciprocity will open avenues for energy absorption, conversion and harvesting, soft robotics, prosthetics and optomechanics.

  4. Theory, Characterization and Applications of Infrared Hyperbolic Metamaterials

    Science.gov (United States)

    Fullager, Daniel B.

    Hyperbolic Metamaterials (HMMs) are engineered structures capable of supporting lightmatter interactions that are not normally observed in naturally occuring material systems. These unusual responses are enabled by an enhancement of the photonic density of states (PDOS) in the material. The PDOS enhancement is a result of deliberately introduced anisotropy via a permittivity sign-change in HMM structures which increases the number and frequency spread of possible wave vectors that propagate in the material. Subwavelength structural features allow effective medium theories to be invoked to construct the k-space isofrequency quadratic curves that, for HMMs, result in the k-space isofrequency contour transitioning from being a bounded surface to an unbounded one. Since the PDOS is the integral of the differential volume between k-space contours, unbounded manifolds lead to the implication of an infinite or otherwise drastically enhanced PDOS. Since stored heat can be thought of as a set of non-radiative electromagnetic modes, in this dissertation we demonstrate that HMMs provide an ideal platform to attempt to modify the thermal/IR emissivity of a material. We also show that HMMs provide a platform for broadband plasmonic sensing. The advent of commercial two photon polymerization tools has enabled the rapid production of nano- and microstructures which can be used as scaffolds for directive infrared scatterers. We describe how such directive components can be used to address thermal management needs in vacuum environments in order to maximize radiative thermal transfer. In this context, the fundamental limitations of enhanced spon- taneous emission due to conjugate impedance matched scatterers are also explored. The HMM/conjugate scatterer system's performance is strongly correlated with the dielectric function of the negative permittivity component of the HMM. In order to fully understand the significance of these engineered materials, we examine in detail the

  5. Perfect-absorption graphene metamaterials for surface-enhanced molecular fingerprint spectroscopy

    Science.gov (United States)

    Guo, Xiangdong; Hu, Hai; Liao, Baoxin; Zhu, Xing; Yang, Xiaoxia; Dai, Qing

    2018-05-01

    Graphene plasmon with extremely strong light confinement and tunable resonance frequency represents a promising surface-enhanced infrared absorption (SEIRA) sensing platform. However, plasmonic absorption is relatively weak (approximately 1%-9%) in monolayer graphene nanostructures, which would limit its sensitivity. Here, we theoretically propose a hybrid plasmon-metamaterial structure that can realize perfect absorption in graphene with a low carrier mobility of 1000 cm2 V-1 s-1. This structure combines a gold reflector and a gold grating to the graphene plasmon structures, which introduce interference effect and the lightning-rod effect, respectively, and largely enhance the coupling of light to graphene. The vibration signal of trace molecules can be enhanced up to 2000-fold at the hotspot of the perfect-absorption structure, enabling the SEIRA sensing to reach the molecular level. This hybrid metal-graphene structure provides a novel path to generate high sensitivity in nanoscale molecular recognition for numerous applications.

  6. Achieving selective interrogation and sub-wavelength resolution in thin plates with embedded metamaterial acoustic lenses

    Energy Technology Data Exchange (ETDEWEB)

    Semperlotti, F., E-mail: fsemperl@nd.edu; Zhu, H. [Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2014-08-07

    In this study, we present an approach to ultrasonic beam-forming and high resolution identification of acoustic sources having critical implications for applications such as structural health monitoring. The proposed concept is based on the design of dynamically tailored structural elements via embedded acoustic metamaterial lenses. This approach provides a completely new alternative to conventional phased-array technology enabling the formation of steerable and collimated (or focused) ultrasonic beams by exploiting a single transducer. Numerical results show that the ultrasonic beam can be steered by simply tuning the frequency of the excitation. Also, the embedded lens can be designed to achieve sub-wavelength resolution to clustered acoustic sources, which is a typical scenario encountered in incipient structural damage.

  7. Asymmetric transmission of acoustic waves in a layer thickness distribution gradient structure using metamaterials

    Directory of Open Access Journals (Sweden)

    Jung-San Chen

    2016-09-01

    Full Text Available This research presents an innovative asymmetric transmission design using alternate layers of water and metamaterial with complex mass density. The directional transmission behavior of acoustic waves is observed numerically inside the composite structure with gradient layer thickness distribution and the rectifying performance of the present design is evaluated. The layer thickness distributions with arithmetic and geometric gradients are considered and the effect of gradient thickness on asymmetric wave propagation is systematically investigated using finite element simulation. The numerical results indicate that the maximum pressure density and transmission through the proposed structure are significantly influenced by the wave propagation direction over a wide range of audible frequencies. Tailoring the thickness of the layered structure enables the manipulation of asymmetric wave propagation within the desired frequency range. In conclusion, the proposed design offers a new possibility for developing directional-dependent acoustic devices.

  8. Real-Time Adaptive Lossless Hyperspectral Image Compression using CCSDS on Parallel GPGPU and Multicore Processor Systems

    Science.gov (United States)

    Hopson, Ben; Benkrid, Khaled; Keymeulen, Didier; Aranki, Nazeeh; Klimesh, Matt; Kiely, Aaron

    2012-01-01

    The proposed CCSDS (Consultative Committee for Space Data Systems) Lossless Hyperspectral Image Compression Algorithm was designed to facilitate a fast hardware implementation. This paper analyses that algorithm with regard to available parallelism and describes fast parallel implementations in software for GPGPU and Multicore CPU architectures. We show that careful software implementation, using hardware acceleration in the form of GPGPUs or even just multicore processors, can exceed the performance of existing hardware and software implementations by up to 11x and break the real-time barrier for the first time for a typical test application.

  9. Hybrid plasmonic/semiconductor nanoparticle monolayer assemblies as hyperbolic metamaterials

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Ozel, Tuncay; Mutlugun, Evren

    2014-01-01

    effective permittivity tensor of the structure. This results in increased photonic density of states and strong enhancement of quantum dot luminescence, in line with recent experimental results. Our findings demonstrate that hyperbolic metamaterials can increase the radiative decay rate of emission centers...

  10. Auxetic Mechanical Metamaterials to Enhance Sensitivity of Stretchable Strain Sensors.

    Science.gov (United States)

    Jiang, Ying; Liu, Zhiyuan; Matsuhisa, Naoji; Qi, Dianpeng; Leow, Wan Ru; Yang, Hui; Yu, Jiancan; Chen, Geng; Liu, Yaqing; Wan, Changjin; Liu, Zhuangjian; Chen, Xiaodong

    2018-03-01

    Stretchable strain sensors play a pivotal role in wearable devices, soft robotics, and Internet-of-Things, yet these viable applications, which require subtle strain detection under various strain, are often limited by low sensitivity. This inadequate sensitivity stems from the Poisson effect in conventional strain sensors, where stretched elastomer substrates expand in the longitudinal direction but compress transversely. In stretchable strain sensors, expansion separates the active materials and contributes to the sensitivity, while Poisson compression squeezes active materials together, and thus intrinsically limits the sensitivity. Alternatively, auxetic mechanical metamaterials undergo 2D expansion in both directions, due to their negative structural Poisson's ratio. Herein, it is demonstrated that such auxetic metamaterials can be incorporated into stretchable strain sensors to significantly enhance the sensitivity. Compared to conventional sensors, the sensitivity is greatly elevated with a 24-fold improvement. This sensitivity enhancement is due to the synergistic effect of reduced structural Poisson's ratio and strain concentration. Furthermore, microcracks are elongated as an underlying mechanism, verified by both experiments and numerical simulations. This strategy of employing auxetic metamaterials can be further applied to other stretchable strain sensors with different constituent materials. Moreover, it paves the way for utilizing mechanical metamaterials into a broader library of stretchable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 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...... photogalvanic effect is a plasmonic analogue of the bulk photovoltaic effect in ferroelectrics....

  12. Add-on unidirectional elastic metamaterial plate cloak

    Science.gov (United States)

    Lee, Min Kyung; Kim, Yoon Young

    2016-02-01

    Metamaterial cloaks control the propagation of waves to make an object invisible or insensible. To manipulate elastic waves in space, a metamaterial cloak is typically embedded in a base system that includes or surrounds a target object. The embedding is undesirable because it structurally weakens or permanently alters the base system. In this study, we propose a new add-on metamaterial elastic cloak that can be placed over and mechanically coupled with a base structure without embedding. We designed an add-on type annular metamaterial plate cloak through conformal mapping, fabricated it and performed cloaking experiments in a thin-plate with a hole. Experiments were performed in a thin plate by using the lowest symmetric Lamb wave centered at 100 kHz. As a means to check the cloaking performance of the add-on elastic plate cloak, possibly as a temporary stress reliever or a so-called “stress bandage”, the degree of stress concentration mitigation and the recovery from the perturbed wave field due to a hole were investigated.

  13. Chiral metamaterials characterisation using the wave propagation retrieval method

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Lavrinenko, Andrei; Malureanu, Radu

    2010-01-01

    In this presentation we extend the wave propagation method for the retrieval of the effective properties to the case of chiral metamaterials with circularly polarised eigenwaves. The method is unambiguous, simple and provides bulk effective parameters. Advantages and constraints are discussed...

  14. The wave attenuation mechanism of the periodic local resonant metamaterial

    Science.gov (United States)

    Chang, I.-Ling; Liang, Zhen-Xian; Kao, Hao-Wei; Chang, Shih-Hsiang; Yang, Chih-Ying

    2018-01-01

    This research discusses the wave propagation behavior and attenuation mechanism of the elastic metamaterial with locally resonant sub-structure. The dispersion relation of the single resonance system, i.e., periodic spring mass system with sub-structure, could be derived based on lattice dynamics and the band gap could be easily identified. The dynamically equivalent properties, i.e., mass and elastic property, of the single resonance system are derived and found to be frequency dependent. Negative effective properties are found in the vicinity of the local resonance. It is examined whether the band gap always coincides with the frequency range of negative effective properties. The wave attenuation mechanism and the characteristic dynamic behavior of the elastic metamaterial are also studied from the energy point of view. From the analysis, it is clarified that the coupled Bragg-resonance band gap is much wider than the narrow-banded local resonance and the corresponding effective material properties at band gap could be either positive or negative. However, the band gap is totally overlapping with the frequency range of negative effective properties for the metamaterial with band gap purely caused by local resonance. The presented analysis can be extended to other forms of elastic metamaterials involving periodic resonator structures.

  15. Arbitrarily thin metamaterial structure for perfect absorption and giant magnification

    DEFF Research Database (Denmark)

    Jin, Yi; Xiao, Sanshui; Mortensen, N. Asger

    2011-01-01

    In our common understanding, for strong absorption or amplification in a slab structure, the desire of reducing the slab thickness seems contradictory to the condition of small loss or gain. In this paper, this common understanding is challenged. It is shown that an arbitrarily thin metamaterial ...

  16. Homogenization of metamaterials: Parameters retrieval methods and intrinsic problems

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Lavrinenko, Andrei

    2010-01-01

    Metamaterials (MTMs) claim a lot of attention worldwide. Description of the MTMs in terms of effective parameters is a simple and useful tool for characterisation of their electromagnetic properties. So a reliable effective parameters restoration method is on demand. In this paper we report about...

  17. Wave propagation phenomena in metamaterials for retrieving of effective parameters

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Ha, S.

    2011-01-01

    In the talk we give an overview of the developed restoration procedures and discuss their pros and cons in connection of assigning effective parameters (EP) to metamaterials (MMs). There are plenty of notorious physical phenomena preserving the unambiguous retrieving of EP, like strong coupling...

  18. Broadband low-frequency sound isolation by lightweight adaptive metamaterials

    Science.gov (United States)

    Liao, Yunhong; Chen, Yangyang; Huang, Guoliang; Zhou, Xiaoming

    2018-03-01

    Blocking broadband low-frequency airborne noises is highly desirable in lots of engineering applications, while it is extremely difficult to be realized with lightweight materials and/or structures. Recently, a new class of lightweight adaptive metamaterials with hybrid shunting circuits has been proposed, demonstrating super broadband structure-borne bandgaps. In this study, we aim at examining their potentials in broadband sound isolation by establishing an analytical model that rigorously combines the piezoelectric dynamic couplings between adaptive metamaterials and acoustics. Sound transmission loss of the adaptive metamaterial is investigated with respect to both the frequency and angular spectrum to demonstrate their sound-insulation effects. We find that efficient sound isolation can indeed be pursued in the broadband bi-spectrum for not only the case of the small resonator's periodicity where only one mode relevant to the mass-spring resonance exists, but also for the large-periodicity scenario, so that the total weight can be even lighter, in which the multiple plate-resonator coupling modes appear. In the latter case, the negative spring stiffness provided by the piezoelectric stack has been utilized to suppress the resonance-induced high acoustic transmission. Such kinds of adaptive metamaterials could open a new approach for broadband noise isolation with extremely lightweight structures.

  19. Electromagnetically induced transparency in metamaterials at near-infrared frequency

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Xiao, Sanshui; Jeppesen, Claus

    2010-01-01

    We employ a planar metamaterial structure composed of a splitring-resonator (SRR) and paired nano-rods to experimentally realize a spectral response at near-infrared frequencies resembling that of electromagnetically induced transparency. A narrow transparency window associated with low loss...

  20. Viscothermal Losses in Double-Negative Acoustic Metamaterials

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; García-Chocano, Victor M.; Sánchez-Dehesa, José

    2017-01-01

    The influence of losses in double-negative metamaterial slabs recently introduced by Graciá-Salgado et al. [Phys. Rev. B 88, 224305 (2013)] is comprehensively studied. Viscous and thermal losses are considered in the linearized Navier-Stokes equations with no flow. Despite the extremely low thick...

  1. Solitons and decoherence in left-handed metamaterials

    International Nuclear Information System (INIS)

    Marklund, Mattias; Shukla, Padma K.; Stenflo, Lennart; Brodin, Gert

    2005-01-01

    We present exact electromagnetic solitary pulses that can be experimentally obtained within nonlinear left-handed metamaterials. The effect of pulse decoherence on the modulation instability of partially incoherent electromagnetic waves is also investigated. The results may contribute to a better understanding of nonlinear electromagnetic pulse propagation in media with negative index of refraction

  2. A metamaterial electromagnetic energy rectifying surface with high harvesting efficiency

    Directory of Open Access Journals (Sweden)

    Xin Duan

    2016-12-01

    Full Text Available A novel metamaterial rectifying surface (MRS for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a harvesting efficiency up to 66.9% under an incident power density of 5 mW/cm2, compared with a simulated efficiency of 72.9%. This high harvesting efficiency makes the proposed MRS an effective receiving device in practical microwave power transmission applications.

  3. 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...

  4. Towards optimal design of locally resonant acoustic metamaterials

    NARCIS (Netherlands)

    Krushynska, A.O.; Kouznetsova, V.; Geers, M.G.D.

    2014-01-01

    The paper presents an in-depth analysis of solid locally resonant acoustic metamaterials (LRAMs) consisting of rubber-coated inclusions. Dispersion properties of two-dimensional LRAMs are studied by means of finite-element modal analysis. For an incompressible rubber, only one practically important

  5. A metamaterial electromagnetic energy rectifying surface with high harvesting efficiency

    Science.gov (United States)

    Duan, Xin; Chen, Xing; Zhou, Lin

    2016-12-01

    A novel metamaterial rectifying surface (MRS) for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a harvesting efficiency up to 66.9% under an incident power density of 5 mW/cm2, compared with a simulated efficiency of 72.9%. This high harvesting efficiency makes the proposed MRS an effective receiving device in practical microwave power transmission applications.

  6. Ultrasensitive Terahertz Waveguide Modulators Using Multilayer Graphene Metamaterials

    DEFF Research Database (Denmark)

    Khromova, I.; Andryieuski, Andrei; Lavrinenko, Andrei

    2014-01-01

    We study terahertz-infrared electromagnetic properties of multilayer graphene- dielectric metamaterial and present novel waveguide-based devices: modulators with high mod- ulation depth ( > 38 dB at 0 : 07 eV graphene’s Fermi energy change) or extreme sensitivity (mod- ulation depth of > 13 : 2 d...

  7. A titanium nitride based metamaterial for applications in the visible

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Saha, Bivas; Liu, Jing

    2013-01-01

    Epitaxially grown TiN/Al0.6Sc0.4N superlattice behaves as a hyperbolic metamaterial (HMM) in the visible range. Since HMMs enhance photonic-density-of-states and reduce lifetime of an emitter, we observed nine times decrease in lifetime of a dye molecule placed close to this HMM. © 2013 The Optic...

  8. A topology optimization method for design of negative permeability metamaterials

    DEFF Research Database (Denmark)

    Diaz, A. R.; Sigmund, Ole

    2010-01-01

    A methodology based on topology optimization for the design of metamaterials with negative permeability is presented. The formulation is based on the design of a thin layer of copper printed on a dielectric, rectangular plate of fixed dimensions. An effective media theory is used to estimate the ...

  9. Water: Promising Opportunities For Tunable All-dielectric Electromagnetic Metamaterials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Kuznetsova, Svetlana M.; Zhukovsky, Sergei

    2015-01-01

    We reveal an outstanding potential of water as an inexpensive, abundant and bio-friendly high-refractive-index material for creating tunable all-dielectric photonic structures and metamaterials. Specifically, we demonstrate thermal, mechanical and gravitational tunability of magnetic and electric...

  10. Wave propagation in metamaterials and effective parameters retrieving

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, S.; Sukhorukov, A.

    2011-01-01

    Metamaterials, as a class of artificial materials with extraordinary electromagnetic properties, require reliable methods of their properties determination. The vast majority of researchers and engineers apply the simple S-parameters based method [1]. Its disadvantage is the ambiguity of the dete...

  11. Achieving highly efficient and broad-angle polarization beam filtering using epsilon-near-zero metamaterials mimicked by metal-dielectric multilayers

    Science.gov (United States)

    Wu, Feng

    2018-03-01

    We report a highly efficient and broad-angle polarization beam filter at visible wavelengths using an anisotropic epsilon-near-zero metamaterial mimicked by a multilayer composed of alternative subwavelength magnesium fluoride and silver layers. The underlying physics can be explained by the dramatic difference between two orthogonal polarizations' iso-frequency curves of anisotropic epsilon-near-zero metamaterials. Transmittance for two orthogonal polarization waves and the polarization extinction ratio are calculated via the transfer matrix method to assess the comprehensive performance of the proposed polarization beam filter. From the simulation results, the proposed polarization beam filter is highly efficient (the polarization extinction ratio is far larger than two orders of magnitude) and has a broad operating angle range (ranging from 30° to 75°). Finally, we show that the proper tailoring of the periodic number enables us to obtain high comprehensive performance of the proposed polarization beam filter.

  12. Induced transparencies in metamaterial waveguides doped with quantum dots

    International Nuclear Information System (INIS)

    Singh, Mahi R; Brzozowski, Marek; Racknor, Chris

    2015-01-01

    The light-mater interaction in quantum dots doped artificial electromagnetic materials such as metamaterial waveguides has been studied. The effect of surface plasmon polaritons (SPPs) on the absorption coefficient of quantum dots in metamaterial waveguides is investigated. The waveguides are made by sandwiching a metamaterial slab between two dielectric material layers. An ensemble of quantum dots are deposited near the waveguide interfaces. The transfer matrix method is used to calculate the SSPs in the waveguide and the density matrix method and Schrödinger equation method are used to calculate the absorption spectrum. It is found that when the thickness of the metamaterial slab is greater than the SPP wavelength the SPP energy is degenerate. However when the thickness of the slab is smaller than that of the SPP wavelength the degeneracy of SPP state splits into odd and even SPP modes due the surface mode interaction (SMI) of the waveguide. We also found that the absorption spectrum has a minima (transparent state) which is due to strong coupling between excitons in quantum dots and SPPs in the waveguide. This transparent state is called the SPP induced transparency. However when the thickness of the slab is smaller than that of the SPP wavelength one transparent state in the absorption spectrum split into two transparent states due to the surface mode interaction. This type of transparency is called the SMI induced transparency. Transparent states can be achieved by applying pulse stress field or an intense laser pulse field. Hence present findings can be used to fabricate the metamaterial optical sensors and switches. (paper)

  13. Directive Emission Obtained by Mu and Epsilon-Near-Zero Metamaterials

    Directory of Open Access Journals (Sweden)

    J. Yang

    2009-06-01

    Full Text Available In this work, we use Mu and Epsilon-Near-Zero (MENZ metamaterials to realize the substrates that can modify the emission of an embedded line source. Simulation results show that the cylindrical waves emitted from the line source can be perfectly converted to plane wave through the MENZ metamaterial slab with planar exit face. Hence the line source together with the metamaterial slab constructs a high directive slab antenna. The directive radiation pattern of the MENZ metamaterial-assisted slab antenna is independent on the thickness of the slab, the position of the line source, and the shape of the entrance face of the slab, but the slab with grooved entrance side will result in stronger far-field intensity. We also show that the MENZ metamaterials can be applied to the design of antenna array. Moreover, compared with the high directive slab antenna obtained by coordinate transformation approach, the MENZ metamaterial-assisted antenna is more preferable.

  14. Origami-inspired, on-demand deployable and collapsible mechanical metamaterials with tunable stiffness

    Science.gov (United States)

    Zhai, Zirui; Wang, Yong; Jiang, Hanqing

    2018-03-01

    Origami has been employed to build deployable mechanical metamaterials through folding and unfolding along the crease lines. Deployable metamaterials are usually flexible, particularly along their deploying and collapsing directions, which unfortunately in many cases leads to an unstable deployed state, i.e., small perturbations may collapse the structure along the same deployment path. Here we create an origami-inspired mechanical metamaterial with on-demand deployability and selective collapsibility through energy analysis. This metamaterial has autonomous deployability from the collapsed state and can be selectively collapsed along two different paths, embodying low stiffness for one path and substantially high stiffness for another path. The created mechanical metamaterial yields load-bearing capability in the deployed direction while possessing great deployability and collapsibility. The principle in this work can be utilized to design and create versatile origami-inspired mechanical metamaterials that can find many applications.

  15. Realization of a thermal cloak-concentrator using a metamaterial transformer.

    Science.gov (United States)

    Liu, Ding-Peng; Chen, Po-Jung; Huang, Hsin-Haou

    2018-02-06

    By combining rotating squares with auxetic properties, we developed a metamaterial transformer capable of realizing metamaterials with tunable functionalities. We investigated the use of a metamaterial transformer-based thermal cloak-concentrator that can change from a cloak to a concentrator when the device configuration is transformed. We established that the proposed dual-functional metamaterial can either thermally protect a region (cloak) or focus heat flux in a small region (concentrator). The dual functionality was verified by finite element simulations and validated by experiments with a specimen composed of copper, epoxy, and rotating squares. This work provides an effective and efficient method for controlling the gradient of heat, in addition to providing a reference for other thermal metamaterials to possess such controllable functionalities by adapting the concept of a metamaterial transformer.

  16. Unlocking New Physics and Enabling Plasmonic and Metamaterial Devices with Improved Materials

    Science.gov (United States)

    2014-11-19

    have   stabilized   the   cubic   phase   of   AlxSc1-­‐xN  by   alloying  AlN  with   scandium   nitride   (ScN),   to...deposit  cubic  TiN/(Al,Sc)N  superlattices.  An   aluminium  concentration  of  72%  in  AlxSc1-­‐xN   (estimated   with

  17. LOW COMPLEXITY HYBRID LOSSY TO LOSSLESS IMAGE CODER WITH COMBINED ORTHOGONAL POLYNOMIALS TRANSFORM AND INTEGER WAVELET TRANSFORM

    Directory of Open Access Journals (Sweden)

    R. Krishnamoorthy

    2012-05-01

    Full Text Available In this paper, a new lossy to lossless image coding scheme combined with Orthogonal Polynomials Transform and Integer Wavelet Transform is proposed. The Lifting Scheme based Integer Wavelet Transform (LS-IWT is first applied on the image in order to reduce the blocking artifact and memory demand. The Embedded Zero tree Wavelet (EZW subband coding algorithm is used in this proposed work for progressive image coding which achieves efficient bit rate reduction. The computational complexity of lower subband coding of EZW algorithm is reduced in this proposed work with a new integer based Orthogonal Polynomials transform coding. The normalization and mapping are done on the subband of the image for exploiting the subjective redundancy and the zero tree structure is obtained for EZW coding and so the computation complexity is greatly reduced in this proposed work. The experimental results of the proposed technique also show that the efficient bit rate reduction is achieved for both lossy and lossless compression when compared with existing techniques.

  18. Characterization of applied fields for ion mobility in traveling wave based structures for lossless ion manipulations (SLIM)

    Energy Technology Data Exchange (ETDEWEB)

    Hamid, Ahmed M.; Prabhakaran Nair Syamala Amma, Aneesh; Garimella, Venkata BS; Ibrahim, Yehia M.; Smith, Richard D.

    2018-03-21

    Ion mobility (IM) is rapidly gaining attention for the analysis of biomolecules due to the ability to distinguish the shapes of ions. However, conventional constant electric field drift tube IM has limited resolving power, constrained by practical limitations on the path length and maximum applied voltage. The implementation of traveling waves (TW) in IM removes the latter limitation, allowing higher resolution to be achieved using extended path lengths. These can be readily obtainable in structures for lossless ion manipulations (SLIM), which are fabricated from electric fields that are generated by appropriate potentials applied to arrays of electrodes patterned on two parallel surfaces. In this work we have investigated the relationship between the various SLIM variables, such as electrode dimensions, inter-surface gap, and the TW applied voltages, that directly impact the fields experienced by ions. Ion simulation and theoretical calculations have been utilized to understand the dependence of SLIM geometry and effective electric field. The variables explored impact both ion confinement and the observed IM resolution in Structures for Lossless Ion Manipulations (SLIM) modules.

  19. Application of reversible denoising and lifting steps with step skipping to color space transforms for improved lossless compression

    Science.gov (United States)

    Starosolski, Roman

    2016-07-01

    Reversible denoising and lifting steps (RDLS) are lifting steps integrated with denoising filters in such a way that, despite the inherently irreversible nature of denoising, they are perfectly reversible. We investigated the application of RDLS to reversible color space transforms: RCT, YCoCg-R, RDgDb, and LDgEb. In order to improve RDLS effects, we propose a heuristic for image-adaptive denoising filter selection, a fast estimator of the compressed image bitrate, and a special filter that may result in skipping of the steps. We analyzed the properties of the presented methods, paying special attention to their usefulness from a practical standpoint. For a diverse image test-set and lossless JPEG-LS, JPEG 2000, and JPEG XR algorithms, RDLS improves the bitrates of all the examined transforms. The most interesting results were obtained for an estimation-based heuristic filter selection out of a set of seven filters; the cost of this variant was similar to or lower than the transform cost, and it improved the average lossless JPEG 2000 bitrates by 2.65% for RDgDb and by over 1% for other transforms; bitrates of certain images were improved to a significantly greater extent.

  20. Terahertz transmission resonances in complementary multilayered metamaterial with deep subwavelength interlayer spacing

    Science.gov (United States)

    Choi, Muhan; Kang, Byungsoo; Yi, Yoonsik; Lee, Seung Hoon; Kim, Inbo; Han, Jae-Hyung; Yi, Minwoo; Ahn, Jaewook; Choi, Choon-Gi

    2016-05-01

    We introduce a flexible multilayered THz metamaterial designed by using the Babinet's principle with the functionality of narrow band-pass filter. The metamaterial gives us systematic way to design frequency selective surfaces working on intended frequencies and bandwidths. It shows highly enhanced transmission of 80% for the normal incident THz waves due to the strong coupling of the two layers of metamaterial complementary to each other.

  1. Origami-based cellular metamaterial with auxetic, bistable, and self-locking properties

    Science.gov (United States)

    Kamrava, Soroush; Mousanezhad, Davood; Ebrahimi, Hamid; Ghosh, Ranajay; Vaziri, Ashkan

    2017-04-01

    We present a novel cellular metamaterial constructed from Origami building blocks based on Miura-ori fold. The proposed cellular metamaterial exhibits unusual properties some of which stemming from the inherent properties of its Origami building blocks, and others manifesting due to its unique geometrical construction and architecture. These properties include foldability with two fully-folded configurations, auxeticity (i.e., negative Poisson’s ratio), bistability, and self-locking of Origami building blocks to construct load-bearing cellular metamaterials. The kinematics and force response of the cellular metamaterial during folding were studied to investigate the underlying mechanisms resulting in its unique properties using analytical modeling and experiments.

  2. Effective material parameter retrieval of anisotropic elastic metamaterials with inherent nonlocality

    Science.gov (United States)

    Lee, Hyung Jin; Lee, Heung Son; Ma, Pyung Sik; Kim, Yoon Young

    2016-09-01

    In this paper, the scattering (S-) parameter retrieval method is presented specifically for anisotropic elastic metamaterials; so far, no retrieval has been accomplished when elastic metamaterials exhibit fully anisotropic behavior. Complex constitutive property and intrinsic scattering behavior of elastic metamaterials make their characterization far more complicated than that for acoustic and electromagnetic metamaterials. In particular, elastic metamaterials generally exhibit anisotropic scattering behavior due to higher scattering modes associated with shear deformation. They also exhibit nonlocal responses to some degrees, which originate from strong multiple scattering interactions even in the long wavelength limit. Accordingly, the conventional S-parameter retrieval methods cannot be directly used for elastic metamaterials, because they determine only the diagonal components in effective tensor property. Also, the conventional methods simply use the analytic inversion formulae for the material characterization so that inherent nonlocality cannot be taken into account. To establish a retrieval method applicable to anisotropic elastic metamaterials, we propose an alternative S-parameter method to deal with full anisotropy of elastic metamaterials. To retrieve the whole effective anisotropic parameter, we utilize not only normal but also oblique wave incidences. For the retrieval, we first retrieve the ratio of the effective stiffness tensor to effective density and then determine the effective density. The proposed retrieval method is validated by characterizing the effective material parameters of various types of non-resonant anisotropic metamaterials. It is found that the whole effective parameters are retrieved consistently regardless of used retrieval conditions in spite of inherent nonlocality.

  3. Focusing: coming to the point in metamaterials

    Science.gov (United States)

    Guenneau, S.; Diatta, A.; McPhedran, R. C.

    2010-04-01

    This paper reviews some properties of lenses in curved and folded optical spaces. The point of the paper is to show some limitations of geometrical optics in the analysis of subwavelength focusing. We first provide a comprehensive derivation for the equation of geodesics in curved optical spaces, which is a tool of choice to design metamaterials in transformation optics. We then analyse the resolution of the image of a line source radiating in the Maxwell fisheye and the Veselago-Pendry slab lens. The former optical medium is deduced from the stereographic projection of a virtual sphere and displays a heterogeneous refractive index n(r) which is proportional to the inverse of 1 + r 2. The latter is described by a homogeneous, but negative, refractive index. It has been suggested that the fisheye makes a perfect lens without negative refraction [Leonhardt, Philbin arxiv:0805.4778v2]. However, we point out that the definition of super-resolution in such a heterogeneous medium should be computed with respect to the wavelength in a homogenised medium, and it is perhaps more adequate to talk about a conjugate image rather than a perfect image (the former does not necessarily contain the evanescent components of the source). We numerically find that both the Maxwell fisheye and a thick silver slab lens lead to a resolution close to λ/3 in transverse magnetic polarisation (electric field pointing orthogonal to the plane). We note a shift of the image plane in the latter lens. We also observe that two sources lead to multiple secondary images in the former lens, as confirmed from light rays travelling along geodesics of the virtual sphere. We further observe resolutions ranging from λ/2 to nearly λ/4 for magnetic dipoles of varying orientations of dipole moments within the fisheye in transverse electric polarisation (magnetic field pointing orthogonal to the plane). Finally, we analyse the Eaton lens for which the source and its image are either located within a unit

  4. Microwave Imaging Sensor Using Compact Metamaterial UWB Antenna with a High Correlation Factor

    Directory of Open Access Journals (Sweden)

    Md. Moinul Islam

    2015-07-01

    Full Text Available The design of a compact metamaterial ultra-wideband (UWB antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. This proposed UWB antenna is made of four metamaterial unit cells, where each cell is an integration of a modified split ring resonator (SRR, capacitive loaded strip (CLS and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A low-cost FR4 substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 1.6 mm, relative permeability of one, relative permittivity of 4.60 and loss tangent of 0.02. The overall antenna size is 19.36 mm × 27.72 mm × 1.6 mm where the electrical dimension is 0.20 λ × 0.28 λ × 0.016 λ at the 3.05 GHz lower frequency band. Voltage Standing Wave Ratio (VSWR measurements have illustrated that this antenna exhibits an impedance bandwidth from 3.05 GHz to more than 15 GHz for VSWR < 2 with an average gain of 4.38 dBi throughout the operating frequency band. The simulations (both HFSS and computer simulation technology (CST and the measurements are in high agreement. A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor.

  5. Polarization-dependent optics using gauge-field metamaterials

    International Nuclear Information System (INIS)

    Liu, Fu; Xiao, Shiyi; Li, Jensen; Wang, Saisai; Hang, Zhi Hong

    2015-01-01

    We show that effective gauge field for photons with polarization-split dispersion surfaces, being realized using uniaxial metamaterials, can be used for polarization control with unique opportunities. The metamaterials with the proposed gauge field correspond to a special choice of eigenpolarizations on the Poincaré sphere as pseudo-spins, in contrary to those from either conventional birefringent crystals or optical active media. It gives rise to all-angle polarization control and a generic route to manipulate photon trajectories or polarizations in the pseudo-spin domain. As demonstrations, we show beam splitting (birefringent polarizer), all-angle polarization control, unidirectional polarization filter, and interferometer as various polarization control devices in the pseudo-spin domain. We expect that more polarization-dependent devices can be designed under the same framework

  6. Ellipsoidal all-dielectric Fano resonant core-shell metamaterials

    Science.gov (United States)

    Reena, Reena; Kalra, Yogita; Kumar, Ajeet

    2018-06-01

    In this paper, ellipsoidal core (Si) and shell (SiO2) metamaterial has been proposed for highly directional properties. At the wavelength of magnetic resonance, Fano dip occurs in the backward scattering cross section and forward scattering enhancement takes place at the same wavelength so that there is an increment in the directivity. Effect on the directivity by changing the length of ellipsoidal nanoparticle along semi-axes has been analyzed. Two Fano resonances have been observed by decreasing the length of the nanoparticle along the semi-axis having electric polarization, where first and second Fano resonances are attributed to the dipole and quadrupole moments, respectively. These Fano resonant wavelengths in ellipsoidal nanoparticle exhibit higher directivity than the Kerker's type scattering or forward scattering shown by symmetrical structures like sphere. So, this core-shell metamaterial can act as an efficient directional nanoantenna.

  7. Improvement in ultraviolet based decontamination rate using meta-materials

    Science.gov (United States)

    Enaki, Nicolae A.; Bazgan, Sergiu; Ciobanu, Nellu; Turcan, Marina; Paslari, Tatiana; Ristoscu, Carmen; Vaseashta, Ashok; Mihailescu, Ion N.

    2017-09-01

    We propose a method of decontamination using photon-crystals consisting of microspheres and fiber optics structures with various geometries. The efficient decontamination using the surface of the evanescent zone of meta-materials opens a new perspective in the decontamination procedures. We propose different topological structures of meta-materials to increase the contact surface of UV radiation with contaminated liquid. Recent observation of the trapping of dielectric particles along the fibers help us propose a new perspective on the new possibilities to trap the viruses, bacteria and other microorganisms from liquids, in this special zone, where the effective UV coherent Raman decontamination becomes possible. The nonlinear theory of the excitation of vibration modes of bio-molecule of viruses and bacteria is revised, taking into consideration the bimodal coherent states in coherent Raman excitation of biomolecules.

  8. Symmetric metamaterials based on flower-shaped structure

    International Nuclear Information System (INIS)

    Tuong, P.V.; Park, J.W.; Rhee, J.Y.; Kim, K.W.; Cheong, H.; Jang, W.H.; Lee, Y.P.

    2013-01-01

    We proposed new models of metamaterials (MMs) based on a flower-shaped structure (FSS), whose “meta-atoms” consist of two flower-shaped metallic parts separated by a dielectric layer. Like the non-symmetric MMs based on cut-wire-pairs or electric ring resonators, the symmetrical FSS demonstrates the negative permeability at GHz frequencies. Employing the results, we designed a symmetric negative-refractive-index MM [a symmetric combined structure (SCS)], which is composed of FSSs and cross continuous wires. The MM properties of the FSS and the SCS are presented numerically and experimentally. - Highlights: • A new designed of sub-wavelength metamaterial, flower-shaped structure was proposed. • Flower-shaped meta-atom illustrated effective negative permeability. • Based on the meta-atom, negative refractive index was conventionally gained. • Negative refractive index was demonstrated with symmetric properties for electromagnetic wave. • Dimensional parameters were studied under normal electromagnetic wave

  9. Wave dynamics and composite mechanics for microstructured materials and metamaterials

    CERN Document Server

    2017-01-01

    This volume deals with topical problems concerning technology and design in construction of modern metamaterials. The authors construct the models of mechanical, electromechanical and acoustical behavior of the metamaterials, which are founded upon mechanisms existing on micro-level in interaction of elementary structures of the material. The empiric observations on the phenomenological level are used to test the created models. The book provides solutions, based on fundamental methods and models using the theory of wave propagation, nonlinear theories and composite mechanics for media with micro- and nanostructure. They include the models containing arrays of cracks, defects, with presence of micro- and nanosize piezoelectric elements and coupled physical-mechanical fields of different nature. The investigations show that the analytical, numerical and experimental methods permit evaluation of the qualitative and quantitative properties of the materials of this sort, with diagnosis of their effective characte...

  10. Membrane-constrained acoustic metamaterials for low frequency sound insulation

    Science.gov (United States)

    Wang, Xiaole; Zhao, Hui; Luo, Xudong; Huang, Zhenyu

    2016-01-01

    We present a constrained membrane-type acoustic metamaterial (CMAM) that employs constraint sticks to add out-of-plane dimensions in the design space of MAM. A CMAM sample, which adopts constraint sticks to suppress vibrations at the membrane center, was fabricated to achieve a sound transmission loss (STL) peak of 26 dB at 140 Hz, with the static areal density of 6.0 kg/m2. The working mechanism of the CMAM as an acoustic metamaterial is elucidated by calculating the averaged normal displacement, the equivalent areal density, and the effective dynamic mass of a unit cell through finite element simulations. Furthermore, the vibration modes of the CMAM indicate that the eigenmodes related to STL dips are shifted into high frequencies, thus broadening its effective bandwidth significantly. Three samples possessing the same geometry and material but different constraint areas were fabricated to illustrate the tunability of STL peaks at low frequencies.

  11. Flexible metamaterial absorbers for stealth applications at terahertz frequencies.

    Science.gov (United States)

    Iwaszczuk, Krzysztof; Strikwerda, Andrew C; Fan, Kebin; Zhang, Xin; Averitt, Richard D; Jepsen, Peter Uhd

    2012-01-02

    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-beam reflection coefficient with the measurement of the far-field bistatic radar cross section of the sample, using a quasi-planar THz wave with a beam diameter significantly larger than the sample dimensions. In this geometry we demonstrate a near-400-fold reduction of the radar cross section at the design 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.

  12. Optical absorption of hyperbolic metamaterial with stochastic surfaces

    DEFF Research Database (Denmark)

    Liu, Jingjing; Naik, Gururaj V.; Ishii, Satoshi

    2014-01-01

    We investigate the absorption properties of planar hyperbolic metamaterials (HMMs) consisting of metal-dielectric multilayers, which support propagating plane waves with anomalously large wavevectors and high photonic-density-of-states over a broad bandwidth. An interface formed by depositing...... indium-tin-oxide nanoparticles on an HMM surface scatters light into the high-k propagating modes of the metamaterial and reduces reflection. We compare the reflection and absorption from an HMM with the nanoparticle cover layer versus those of a metal film with the same thickness also covered...... with the nanoparticles. It is predicted that the super absorption properties of HMM show up when exceedingly large amounts of high-k modes are excited by strong plasmonic resonances. In the case that the coupling interface is formed by non-resonance scatterers, there is almost the same enhancement in the absorption...

  13. Fine tuning and MOND in a metamaterial "multiverse".

    Science.gov (United States)

    Smolyaninov, Igor I; Smolyaninova, Vera N

    2017-08-14

    We consider the recently suggested model of a multiverse based on a ferrofluid. When the ferrofluid is subjected to a modest external magnetic field, the nanoparticles inside the ferrofluid form small hyperbolic metamaterial domains, which from the electromagnetic standpoint behave as individual "Minkowski universes" exhibiting different "laws of physics", such as different strength of effective gravity, different versions of modified Newtonian dynamics (MOND) and different radiation lifetimes. When the ferrofluid "multiverse" is populated with atomic or molecular species, and these species are excited using an external laser source, the radiation lifetimes of atoms and molecules in these "universes" depend strongly on the individual physical properties of each "universe" via the Purcell effect. Some "universes" are better fine-tuned than others to sustain the excited states of these species. Thus, the ferrofluid-based metamaterial "multiverse" may be used to study models of MOND and to illustrate the fine-tuning mechanism in cosmology.

  14. Resonance transparency with low-loss in toroidal planar metamaterial

    Science.gov (United States)

    Xiang, Tianyu; Lei, Tao; Hu, Sen; Chen, Jiao; Huang, Xiaojun; Yang, Helin

    2018-03-01

    A compact planar construction composed of asymmetric split ring resonators was designed with a low-loss, high Q-factor resonance transparency at microwave frequency. The singularity property of the proposed metamaterial owing to the enhanced toroidal dipole T is demonstrated via numerical and experimental methods. The transmission peak can reach up to 0.91 and the loss is perfectly repressed, which can be testified by radiated power, H-field distributions, and the imaginary parts of effective permittivity and permeability. The designed planar metamaterial may have numerous potential applications at microwave, terahertz, and optical frequency, e.g., for ultrasensitive sensing, slow-light devices, lasing spacers, even invisible information transfer.

  15. Elastic metamaterials for tuning circular polarization of electromagnetic waves.

    Science.gov (United States)

    Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A

    2016-06-20

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

  16. A Microring Resonator Based Negative Permeability Metamaterial Sensor

    Directory of Open Access Journals (Sweden)

    Yao-Zhong Lan

    2011-08-01

    Full Text Available Metamaterials are artificial multifunctional materials that acquire their material properties from their structure, rather than inheriting them directly from the materials they are composed of, and they may provide novel tools to significantly enhance the sensitivity and resolution of sensors. In this paper, we derive the dispersion relation of a cylindrical dielectric waveguide loaded on a negative permeability metamaterial (NPM layer, and compute the resonant frequencies and electric field distribution of the corresponding Whispering-Gallery-Modes (WGMs. The theoretical resonant frequency and electric field distribution results are in good agreement with the full wave simulation results. We show that the NPM sensor based on a microring resonator possesses higher sensitivity than the traditional microring sensor since with the evanescent wave amplification and the increase of NPM layer thickness, the sensitivity will be greatly increased. This may open a door for designing sensors with specified sensitivity.

  17. Broadband infrared metamaterial absorber based on anodic aluminum oxide template

    Science.gov (United States)

    Yang, Jingfan; Qu, Shaobo; Ma, Hua; Wang, Jiafu; Yang, Shen; Pang, Yongqiang

    2018-05-01

    In this work, a broadband infrared metamaterial absorber is proposed based on trapezoid-shaped anodic aluminum oxide (AAO) template. Unlike traditional metamaterial absorber constructed from metal-dielectric-metal sandwich structure, our proposed absorber is composed of trapezoid-shaped AAO template with metallic nanowires inside. The infrared absorption efficiency is numerically calculated and the mechanism analysis is given in the paper. Owing to the superposition of multiple resonances produced by the nanowires with different heights, the infrared metamatrial absorber can keep high absorption efficiency during broad working wavelength band from 3.4 μm to 6.1 μm. In addition, the resonance wavelength is associated with the height of nanowires, which indicates that the resonance wavelength can be modulated flexibly through changing the heights of nanowires. This kind of design can also be adapted to other wavelength regions.

  18. Photonic band gap spectra in Octonacci metamaterial quasicrystals

    Science.gov (United States)

    Brandão, E. R.; Vasconcelos, M. S.; Albuquerque, E. L.; Fulco, U. L.

    2017-02-01

    In this work we study theoretically the photonic band gap spectra for a one-dimensional quasicrystal made up of SiO2 (layer A) and a metamaterial (layer B) organized following the Octonacci sequence, where its nth-stage Sn is given by the inflation rule Sn =Sn - 1Sn - 2Sn - 1 for n ≥ 3 , with initial conditions S1 = A and S2 = B . The metamaterial is characterized by a frequency dependent electric permittivity ε(ω) and magnetic permeability μ(ω) . The polariton dispersion relation is obtained analytically by employing a theoretical calculation based on a transfer-matrix approach. A quantitative analysis of the spectra is then discussed, stressing the distribution of the allowed photonic band widths for high generations of the Octonacci structure, which depict a self-similar scaling property behavior, with a power law depending on the common in-plane wavevector kx .

  19. Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS

    Directory of Open Access Journals (Sweden)

    Kyeongseob Kim

    2016-04-01

    Full Text Available A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS. To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm to 6.4 cm.

  20. Metal-dielectric metamaterials for guided wave silicon photonics.

    Science.gov (United States)

    Lupu, A; Dubrovina, N; Ghasemi, R; Degiron, A; de Lustrac, A

    2011-11-21

    The aim of the present paper is to investigate the potential of metallic metamaterials for building optical functions in guided wave optics at 1.5 µm. A significant part of this work is focused on the optimization of the refractive index variation associated with localized plasmon resonances. The minimization of metal related losses is specifically addressed as well as the engineering of the resonance frequency of the localized plasmons. Our numerical modeling results show that a periodic chain of gold cut wires placed on the top of a 100 nm silicon waveguide makes it possible to achieve a significant index variation in the vicinity of the metamaterial resonance and serve as building blocks for implementing optical functions. The considered solutions are compatible with current nano-fabrication technologies. © 2011 Optical Society of America

  1. Back to basics: history of photonic crystals and metamaterials

    Science.gov (United States)

    Soukoulis, Costas M.

    2018-04-01

    We will review the history of photonic crystals and overview of the theoretical and experimental efforts in obtaining a photonic bandgap, a frequency band in three-dimensional dielectric structures in which electromagnetic (EM) waves are forbidden, is presented. Many experimental groups all over the world still employ this woodpile structure to fabricate PCs at optical wavelengths, waveguides, enhance nanocavities, and produce nanolasers with a low threshold limit. We have been focused on a new class of materials, the so-called metamaterials (MMs) or negative-index materials, which exhibit highly unusual electromagnetic properties and hold promise for new device applications. Metamaterials can be designed to exhibit both electric and magnetic resonances that can be separately tuned to occur in frequency bands from megahertz to terahertz frequencies, and hope-fully to the visible region of the EM spectrum.

  2. Thin randomly aligned hierarchical carbon nanotube arrays as ultrablack metamaterials

    Science.gov (United States)

    De Nicola, Francesco; Hines, Peter; De Crescenzi, Maurizio; Motta, Nunzio

    2017-07-01

    Ultrablack metamaterials are artificial materials able to harvest all the incident light regardless of wavelength, angle, or polarization. Here, we show the ultrablack properties of randomly aligned hierarchical carbon nanotube arrays with thicknesses below 200 nm. The thin coatings are realized by solution processing and dry-transfer deposition on different substrates. The hierarchical surface morphology of the coatings is biomimetic and provides a large effective area that improves the film optical absorption. Also, such a morphology is responsible for the moth-eye effect, which leads to the omnidirectional and polarization-independent suppression of optical reflection. The films exhibit an emissivity up to 99.36% typical of an ideal black body, resulting in the thinnest ultrablack metamaterial ever reported. Such a material may be exploited for thermal, optical, and optoelectronic devices such as heat sinks, optical shields, solar cells, light and thermal sensors, and light-emitting diodes.

  3. Babinet's principle for optical frequency metamaterials and nanoantennas

    Science.gov (United States)

    Zentgraf, T.; Meyrath, T. P.; Seidel, A.; Kaiser, S.; Giessen, H.; Rockstuhl, C.; Lederer, F.

    2007-07-01

    We consider Babinet’s principle for metamaterials at optical frequencies and include realistic conditions which deviate from the theoretical assumptions of the classic principle such as an infinitely thin and perfectly conducting metal layer. It is shown that Babinet’s principle associates not only transmission and reflection between a structure and its complement but also the field modal profiles of the electromagnetic resonances as well as effective material parameters—a critical concept for metamaterials. Also playing an important role in antenna design, Babinet’s principle is particularly interesting to consider in this case where the metasurfaces and their complements can be regarded as variations on a folded dipole antenna array and patch antenna array, respectively.

  4. Advanced Numerical and Theoretical Methods for Photonic Crystals and Metamaterials

    Science.gov (United States)

    Felbacq, Didier

    2016-11-01

    This book provides a set of theoretical and numerical tools useful for the study of wave propagation in metamaterials and photonic crystals. While concentrating on electromagnetic waves, most of the material can be used for acoustic (or quantum) waves. For each presented numerical method, numerical code written in MATLAB® is presented. The codes are limited to 2D problems and can be easily translated in Python or Scilab, and used directly with Octave as well.

  5. Theoretical Modeling and Electromagnetic Response of Complex Metamaterials

    Science.gov (United States)

    2017-03-06

    Controlling Sound with Acoustic Metamaterials,” Nature Reviews Materials, Vol. 1, No. 16001, February 16, 2016, (invited paper). DISTRIBUTION A...Khanikaev*, and A. Alù, “Floquet Topological Insulators for Sound ,” Nature Communications, Vol. 7, No. 11744 (11 pages), June 17, 2016, online at...topological insulators for photons and phonons, new concepts based on parity-time symmetric metasurfaces, and various advances in electromagnetic and acoustic

  6. Broadband absorption through extended resonance modes in random metamaterials

    International Nuclear Information System (INIS)

    Hao, J.; Niemiec, R.; Lheurette, É.; Lippens, D.; Burgnies, L.

    2016-01-01

    The properties of disordered metamaterial absorbers are analyzed on the basis of numerical simulations and experimental characterizations. A broadening of the absorption spectrum is clearly evidenced. This effect is the consequence of both the coupling between nearby resonators leading to the occurrence of extended magnetic resonance modes and the interconnection of elementary particles yielding the definition of resonating clusters. The angular robustness of the absorbing structure under oblique incidence is also demonstrated for a wide domain of angles.

  7. Extension of the Multipole Approach to Random Metamaterials

    Directory of Open Access Journals (Sweden)

    A. Chipouline

    2012-01-01

    Full Text Available Influence of the short-range lateral disorder in the meta-atoms positioning on the effective parameters of the metamaterials is investigated theoretically using the multipole approach. Random variation of the near field quasi-static interaction between metaatoms in form of double wires is shown to be the reason for the effective permittivity and permeability changes. The obtained analytical results are compared with the known experimental ones.

  8. Observation of asymmetric electromagnetic field profiles in chiral metamaterials

    Science.gov (United States)

    Hisamoto, Nobuyuki; Ueda, Tetsuya; Sawada, Kei; Tomita, Satoshi

    2018-02-01

    We experimentally observe asymmetric electromagnetic field profiles along two-dimensional chiral metamaterials. The asymmetric field profiles depending on the chirality and the operation frequency have been reproduced well by the numerical simulation. Around a chiral meta-atom, distribution of a Poynting vector is found to be shifted asymmetrically. These results are explained in terms of an analogy with the side-jump mechanism in the electronic anomalous Hall systems.

  9. Near-Field Interaction of Closed Cells for Metamaterial Creation

    Directory of Open Access Journals (Sweden)

    Mironchev Aleksandr

    2016-01-01

    Full Text Available This article presents the results of numerical and computer modeling of the flat closed conductor with different variants of arrangement. The interaction of the conductors is examined and the results of active and reactive part of the Poynting vector for each structure is presented. According to the results the model with identical parameters for each element was built and examined for the presence of metamaterial properties.

  10. External occulter edge scattering control using metamaterials for exoplanet detection

    Science.gov (United States)

    Bendek, Eduardo A.; Sirbu, Dan; Liu, Zhaowei; Martin, Stefan; Lu, Dylan

    2015-09-01

    Direct imaging of earth-like exoplanets in the Habitable Zone of sun-like stars requires image contrast of ~10^10 at angular separations of around a hundred milliarcseconds. One approach for achieving this performance is to fly a starshade at a long distance in front of the telescope, shading the telescope from the direct starlight, but allowing planets around the star to be seen. The starshade is positioned so that sunlight falls on the surface away from the telescope, so the sun does not directly illuminate it. However, sunlight scattered from the starshade edge can enter the telescope, raising the background light level and potentially preventing the starshade from delivering the required contrast. As a result, starshade edge design has been identified as one of the highest priority technology gaps for external occulter missions in the NASAs Exoplanet Exploration Program Technology Plan 2013. To reduce the sunlight edge scatter to an acceptable level, the edge Radius Of Curvature (ROC) should be 1μm or less (commercial razor blades have ROC of a few hundred nanometer). This poses a challenging manufacturing requirement and may make the occulter difficult to handle. In this paper we propose an alternative approach to controlling the edge scattering by applying a flexible metamaterial to the occulter edge. Metamaterials are artificially structured materials, which have been designed to display properties not found in natural materials. Metamaterials can be designed to direct the scatter at planned incident angles away from the space telescope, thereby directly decreasing the contaminating background light. Reduction of the background light translates into shorter integration time to characterize a target planet and therefore improves the efficiency of the observations. As an additional benefit, metamaterials also have potential to produce increased tolerance to edge defects.

  11. Unraveling metamaterial properties in zigzag-base folded sheets.

    Science.gov (United States)

    Eidini, Maryam; Paulino, Glaucio H

    2015-09-01

    Creating complex spatial objects from a flat sheet of material using origami folding techniques has attracted attention in science and engineering. In the present work, we use the geometric properties of partially folded zigzag strips to better describe the kinematics of known zigzag/herringbone-base folded sheet metamaterials such as Miura-ori. Inspired by the kinematics of a one-degree of freedom zigzag strip, we introduce a class of cellular folded mechanical metamaterials comprising different scales of zigzag strips. This class of patterns combines origami folding techniques with kirigami. Using analytical and numerical models, we study the key mechanical properties of the folded materials. We show that our class of patterns, by expanding on the design space of Miura-ori, is appropriate for a wide range of applications from mechanical metamaterials to deployable structures at small and large scales. We further show that, depending on the geometry, these materials exhibit either negative or positive in-plane Poisson's ratios. By introducing a class of zigzag-base materials in the current study, we unify the concept of in-plane Poisson's ratio for similar materials in the literature and extend it to the class of zigzag-base folded sheet materials.

  12. Super Unit Cells in Aperture-Based Metamaterials

    Directory of Open Access Journals (Sweden)

    Dragan Tanasković

    2015-01-01

    Full Text Available An important class of electromagnetic metamaterials are aperture-based metasurfaces. Examples include extraordinary optical transmission arrays and double fishnets with negative refractive index. We analyze a generalization of such metamaterials where a simple aperture is now replaced by a compound object formed by superposition of two or more primitive objects (e.g., rectangles, circles, and ellipses. Thus obtained “super unit cell” shows far richer behavior than the subobjects that comprise it. We show that nonlocalities introduced by overlapping simple subobjects can be used to produce large deviations of spectral dispersion even for small additive modifications of the basic geometry. Technologically, some super cells may be fabricated by simple spatial shifting of the existing photolithographic masks. In our investigation we applied analytical calculations and ab initio finite element modeling to prove the possibility to tailor the dispersion including resonances for plasmonic nanocomposites by adjusting the local geometry and exploiting localized interactions at a subwavelength level. Any desired form could be defined using simple primitive objects, making the situation a geometrical analog of the case of series expansion of a function. Thus an additional degree of tunability of metamaterials is obtained. The obtained designer structures can be applied in different fields like waveguiding and sensing.

  13. Tunneling times in bianisotropic, dispersive and absorptive metamaterials

    International Nuclear Information System (INIS)

    Radosavljević, Sanja; Radovanović, Jelena; Milanović, Vitomir

    2016-01-01

    Tunneling times in complex bianisotropic materials have been examined in detail, with absorption and dispersion taken into account. Tunneling is characterized by the dwell and the phase tunneling time. In this paper, we have developed a theoretical model and derived the appropriate expressions for each of these quantities, as well as a relationship between them and the corresponding expression for the energy density. The model has been verified through numerical calculations based on experimental data. We have distinguished cases in which the phases of transmitted and incident wave match each other, and showed that for small angles of incidence, the time that the wave spends inside the barrier can be approximated as a linear function of the barrier width. The Hartman effect has been detected, although for very thick layers of metamaterial. - Highlights: • We analyze the tunneling times in bianisotropic, dispersive and absorptive metamaterials. • Conditions of zero phase tunneling time are identified for a range of frequencies of interest. • The Hartman effect has been detected for very thick barriers of metamaterial.

  14. Tunneling times in bianisotropic, dispersive and absorptive metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Radosavljević, Sanja [School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade (Serbia); Photonics Research Group, Ghent University – imec, Sint-Pietersnieuwstraat 41, 9000 Ghent (Belgium); Radovanović, Jelena, E-mail: radovanovic@etf.bg.ac.rs [School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade (Serbia); Milanović, Vitomir [School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, 11120 Belgrade (Serbia)

    2016-12-09

    Tunneling times in complex bianisotropic materials have been examined in detail, with absorption and dispersion taken into account. Tunneling is characterized by the dwell and the phase tunneling time. In this paper, we have developed a theoretical model and derived the appropriate expressions for each of these quantities, as well as a relationship between them and the corresponding expression for the energy density. The model has been verified through numerical calculations based on experimental data. We have distinguished cases in which the phases of transmitted and incident wave match each other, and showed that for small angles of incidence, the time that the wave spends inside the barrier can be approximated as a linear function of the barrier width. The Hartman effect has been detected, although for very thick layers of metamaterial. - Highlights: • We analyze the tunneling times in bianisotropic, dispersive and absorptive metamaterials. • Conditions of zero phase tunneling time are identified for a range of frequencies of interest. • The Hartman effect has been detected for very thick barriers of metamaterial.

  15. Nonlinear metamaterials for electromagnetic energy harvesting (Conference Presentation)

    Science.gov (United States)

    Oumbe Tekam, Gabin Thibaut; Ginis, Vincent; Seetharamdoo, Divitha; Danckaert, Jan

    2016-09-01

    Surrounded by electromagnetic radiation coming from wireless power transfer to consumer devices such as mobile phones, computers and television, our society is facing the scientific and technological challenge to recover energy that is otherwise lost to the environment. Energy harvesting is an emerging field of research focused on this largely unsolved problem, especially in the microwave regime. Metamaterials provide a very promising platform to meet this purpose. These artificial materials are made from subwavelength building blocks, and can be designed by resonate at particular frequencies, depending on their shape, geometry, size, and orientation. In this work, we show that an efficient electromagnetic energy harvester can be design by inserting a nonlinear element directly within the metamaterial unit cell, leading to the conversion of RF input power to DC charge accumulation. The electromagnetic energy harvester operating at microwave frequencies is built from a cut-wire metasurface, which operates as a quasistatic electric dipole resonator. Using the equivalent electrical circuit, we design the parameters to tune the resonance frequency of the harvester at the desired frequency, and we compare these results with numerical simulations. Finally, we discuss the efficiency of our metamaterial energy harvesters. This work potentially offers a variety of applications, for example in the telecommunications industry to charge phones, in robotics to power microrobots, and also in medicine to advance pacemakers or health monitoring sensors.

  16. MODOS GUIADOS EM SLABS METAMATERIAIS GUIDED MODES IN METAMATERIAL SLABS

    Directory of Open Access Journals (Sweden)

    Leonardo André Ambrosio

    2006-12-01

    Full Text Available Este trabalho apresenta um estudo de revisão de modos propagantes em um guia-de-onda slab constituído de materiais com índices de refração negativo, os chamados metamateriais, Mostra-se que os modos guiados em um slab metamaterial possuem algumas propriedades particulares, tais como a propagação de ondas lentas simétricas ou anti-simétricas, a ausência de modos fundamentais para ondas rápidas e a possibilidade de propagação de ondas guiadas em um meio menos denso. A análise é baseada em expansões de campo no guia e nos espaços superior e inferior ao mesmo.This paper presents a review of the propagation modes in a slab waveguide consisting of negative refraction index materials, known as metamaterials. Some particular properties of guided modes in a metamaterial slab, such as slow symmetric or antisymmetric slow wave propagation, the absence of fundamental modes for fast waves and the possibility of guided waves in a less dense medium. The analysis is based on field expansions in the guide and the upper and lower spaces of it.

  17. Multimaterial Control of Instability in Soft Mechanical Metamaterials

    Science.gov (United States)

    Janbaz, Shahram; McGuinness, Molly; Zadpoor, Amir A.

    2018-06-01

    Soft mechanical metamaterials working on the basis of instability have numerous potential applications in the context of "machine materials." Controlling the onset of instability is usually required when rationally designing such metamaterials. We study the isolated and modulated effects of geometrical design and material distribution on the onset of instability in multimaterial cellular metamaterials. We use multimaterial additive manufacturing to fabricate cellular specimens whose unit cells are divided into void space, a square element, and an intermediate ligament. The ratio of the elastic modulus of the ligament to that of the square element [(EL)/(ES)] is changed by using different material types. Computational models are also developed, validated against experimental observations, and used to study a wide range of possible designs. The critical stress can be adjusted independently from the critical strain by changing the material type while keeping [(EL)/(ES)] constant. The critical strain shows a power-law relationship with [(EL)/(ES)] within the range [(EL)/(ES)]=0.1 - 10 . The void shape design alters the critical strain by up to threefold, while the combined effects of the void shape and material distribution cause up to a ninefold change in the critical strain. Our findings highlight the strong influence of material distribution on the onset of the instability and buckling mode.

  18. FDTD-SPICE for Characterizing Metamaterials Integrated with Electronic Circuits

    Directory of Open Access Journals (Sweden)

    Zhengwei Hao

    2012-01-01

    Full Text Available A powerful time-domain FDTD-SPICE simulator is implemented and applied to the broadband analysis of metamaterials integrated with active and tunable circuit elements. First, the FDTD-SPICE modeling theory is studied and details of interprocess communication and hybridization of the two techniques are discussed. To verify the model, some simple cases are simulated with results in both time domain and frequency domain. Then, simulation of a metamaterial structure constructed from periodic resonant loops integrated with lumped capacitor elements is studied, which demonstrates tuning resonance frequency of medium by changing the capacitance of the integrated elements. To increase the bandwidth of the metamaterial, non-Foster transistor configurations are integrated with the loops and FDTD-SPICE is applied to successfully bridge the physics of electromagnetic and circuit topologies and to model the whole composite structure. Our model is also applied to the design and simulation of a metasurface integrated with nonlinear varactors featuring tunable reflection phase characteristic.

  19. Displacement Talbot lithography: an alternative technique to fabricate nanostructured metamaterials

    Science.gov (United States)

    Le Boulbar, E. D.; Chausse, P. J. P.; Lis, S.; Shields, P. A.

    2017-06-01

    Nanostructured materials are essential for many recent electronic, magnetic and optical devices. Lithography is the most common step used to fabricate organized and well calibrated nanostructures. However, feature sizes less than 200 nm usually require access to deep ultraviolet photolithography, e-beam lithography or soft lithography (nanoimprinting), which are either expensive, have low-throughput or are sensitive to defects. Low-cost, high-throughput and low-defect-density techniques are therefore of interest for the fabrication of nanostructures. In this study, we investigate the potential of displacement Talbot lithography for the fabrication of specific structures of interest within plasmonic and metamaterial research fields. We demonstrate that nanodash arrays and `fishnet'-like structures can be fabricated by using a double exposure of two different linear grating phase masks. Feature sizes can be tuned by varying the exposure doses. Such lithography has been used to fabricate metallic `fishnet'-like structures using a lift-off technique. This proof of principle paves the way to a low-cost, high-throughput, defect-free and large-scale technique for the fabrication of structures that could be useful for metamaterial and plasmonic metasurfaces. With the development of deep ultraviolet displacement Talbot lithography, the feature dimensions could be pushed lower and used for the fabrication of optical metamaterials in the visible range.

  20. Lossless synthesis of graphene nanosheets decorated with tiny cadmium sulfide quantum dots with excellent nonlinear optical properties

    International Nuclear Information System (INIS)

    Feng Miao; Zhan Hongbing; Sun Ruiqing; Chen Yu

    2010-01-01

    The implantation and growth of metal nanoparticles on graphene nanosheets (GNS) leads directly to severe damage to the regular structure of the graphene sheets, which disrupts the extended π conjugation, resulting in an impaired device performance. In this paper, we describe a facile approach for achieving the lossless formation of graphene composite decorated with tiny cadmium sulfide quantum dots (QDs) with excellent nonlinear optical properties by using benzyl mercaptan (BM) as the interlinker. The mercapto substituent of BM binds to the CdS QDs during their nucleation and growth process, and then the phenyl comes into contact with the GNS via the π-π stacking interaction. Using this strategy, CdS QDs with an average diameter of 3 nm are uniformly dispersed over the surface of graphene, and the resulting QD-graphene composite exhibits excellent optical limiting properties, mainly contributed by nonlinear scattering and nonlinear absorption, upon both 532 and 1064 nm excitations, in the nanosecond laser pulse regime.