Showing papers on "Metamaterial published in 2014"
TL;DR: This Review focuses on recent developments on flat, ultrathin optical components dubbed 'metasurfaces' that produce abrupt changes over the scale of the free-space wavelength in the phase, amplitude and/or polarization of a light beam.
Abstract: Metamaterials are artificially fabricated materials that allow for the control of light and acoustic waves in a manner that is not possible in nature. This Review covers the recent developments in the study of so-called metasurfaces, which offer the possibility of controlling light with ultrathin, planar optical components. Conventional optical components such as lenses, waveplates and holograms rely on light propagation over distances much larger than the wavelength to shape wavefronts. In this way substantial changes of the amplitude, phase or polarization of light waves are gradually accumulated along the optical path. This Review focuses on recent developments on flat, ultrathin optical components dubbed 'metasurfaces' that produce abrupt changes over the scale of the free-space wavelength in the phase, amplitude and/or polarization of a light beam. Metasurfaces are generally created by assembling arrays of miniature, anisotropic light scatterers (that is, resonators such as optical antennas). The spacing between antennas and their dimensions are much smaller than the wavelength. As a result the metasurfaces, on account of Huygens principle, are able to mould optical wavefronts into arbitrary shapes with subwavelength resolution by introducing spatial variations in the optical response of the light scatterers. Such gradient metasurfaces go beyond the well-established technology of frequency selective surfaces made of periodic structures and are extending to new spectral regions the functionalities of conventional microwave and millimetre-wave transmit-arrays and reflect-arrays. Metasurfaces can also be created by using ultrathin films of materials with large optical losses. By using the controllable abrupt phase shifts associated with reflection or transmission of light waves at the interface between lossy materials, such metasurfaces operate like optically thin cavities that strongly modify the light spectrum. Technology opportunities in various spectral regions and their potential advantages in replacing existing optical components are discussed.
4,613 citations
TL;DR: Digital metamaterials consisting of two kinds of unit cells whose different phase responses allow them to act as ‘0’ and ‘1’ bits are developed to enable controlled manipulation of electromagnetic waves.
Abstract: Smart materials offering great freedom in manipulating electromagnetic radiation have been developed. This exciting new concept was realized by Tie Jun Cui and co-workers at the Southeast University, China, who developed digital metamaterials consisting of two kinds of unit cells whose different phase responses allow them to act as ‘0’ and ‘1’ bits. These cells can be judiciously arranged in sequences to enable controlled manipulation of electromagnetic waves. This is one-bit coding; higher-bit coding is possible by employing more kinds of unit cells. The researchers developed a metamaterial cell whose binary response can be controlled by a biased diode. By using a field-programmable gate array, they demonstrated that this digital metamaterial can be programmed. Such metamaterials are attractive for controlling radiation beams in antennas and for realizing other ‘smart’ metamaterials.
1,767 citations
Posted Content•
TL;DR: In this paper, Wu et al. proposed a digital metamaterial with two kinds of unit cells with 0 and π phase responses, which they named as "0" and "1" elements.
Abstract: As artificial structures, metamaterials are usually described by macroscopic effective medium parameters, which are named as "analog metamaterials". Here, we propose "digital metamaterials" in two steps. Firstly, we present "coding metamaterials" that are composed of only two kinds of unit cells with 0 and {\pi} phase responses, which we name as "0" and "1" elements. By coding "0" and "1" elements with controlled sequences (i.e., 1-bit coding), we can manipulate electromagnetic (EM) waves and realize different functionalities. The concept of coding metamaterial can be extended from 1-bit coding to 2-bit or more. In 2-bit coding, four kinds of unit cells with phase responses 0, {\pi}/2, {\pi}, and 3{\pi}/2 are required to mimic "00", "01", "10" and "11" elements, which have larger freedom to control EM waves. Secondly, we propose a unique metamaterial particle which has either "0" or "1" response controlled by a biased diode. Based on the particle, we present "digital metamaterials" with unit cells having either "0" or "1" state. Using the field-programmable gate array, we realize to control the digital metamaterial digitally. By programming different coding sequences, a single digital metamaterial has distinct abilities in manipulating EM waves, realizing the "programming metamaterials". The above concepts and physical phenomena are confirmed by numerical simulations and experiments through metasurfaces.
1,528 citations
TL;DR: A class of microarchitected materials that maintain a nearly constant stiffness per unit mass density, even at ultralow density is reported, which derives from a network of nearly isotropic microscale unit cells with high structural connectivity and nanoscale features, whose structural members are designed to carry loads in tension or compression.
Abstract: The mechanical properties of ordinary materials degrade substantially with reduced density because their structural elements bend under applied load. We report a class of microarchitected materials that maintain a nearly constant stiffness per unit mass density, even at ultralow density. This performance derives from a network of nearly isotropic microscale unit cells with high structural connectivity and nanoscale features, whose structural members are designed to carry loads in tension or compression. Production of these microlattices, with polymers, metals, or ceramics as constituent materials, is made possible by projection microstereolithography (an additive micromanufacturing technique) combined with nanoscale coating and postprocessing. We found that these materials exhibit ultrastiff properties across more than three orders of magnitude in density, regardless of the constituent material.
1,525 citations
TL;DR: This work presents an alternative approach to plasmonic metasurfaces by replacing the metallic resonators with high-refractive-index silicon cut-wires in combination with a silver ground plane, and demonstrates optical vortex beam generation using a meta-reflectarray with an azimuthally varied phase profile.
Abstract: Plasmonic metasurfaces have recently attracted much attention due to their ability to abruptly change the phase of light, allowing subwavelength optical elements for polarization and wavefront control. However, most previously demonstrated metasurface designs suffer from low coupling efficiency and are based on metallic resonators, leading to ohmic loss. Here, we present an alternative approach to plasmonic metasurfaces by replacing the metallic resonators with high-refractive-index silicon cut-wires in combination with a silver ground plane. We experimentally demonstrate that this meta-reflectarray can be used to realize linear polarization conversion with more than 98% conversion efficiency over a 200 nm bandwidth in the short-wavelength infrared band. We also demonstrate optical vortex beam generation using a meta-reflectarray with an azimuthally varied phase profile. The vortex beam generation is shown to have high efficiency over a wavelength range from 1500 to 1600 nm. The use of dielectric resonato...
939 citations
TL;DR: In this paper, the authors describe recent progress in the area of metasurfaces formed from plasmonic meta-atoms and identify some areas ripe for future research and indicate likely avenues for future device development.
Abstract: Metamaterials enable the tailoring of properties like dielectric permittivity and magnetic permeability. Electromagnetic excitations of metamaterial constituents and their interactions are reviewed, as well as promising future directions. Despite the extraordinary degree of interest in optical metamaterials in recent years, the hoped-for devices and applications have, in large part, yet to emerge. It is becoming clear that the first generation of metamaterial-based devices will most probably arise from their two-dimensional equivalents — metasurfaces. In this Review, we describe recent progress in the area of metasurfaces formed from plasmonic meta-atoms. In particular, we approach the subject from the perspective of the fundamental excitations supported by the meta-atoms and the interactions between them. We also identify some areas ripe for future research and indicate likely avenues for future device development.
858 citations
TL;DR: Two approaches are presented to achieve the possibility of miniaturized, potentially integrable, wave-based computing systems that are thinner than conventional lens-based optical signal and data processors by several orders of magnitude.
Abstract: We introduce the concept of metamaterial analog computing, based on suitably designed metamaterial blocks that can perform mathematical operations (such as spatial differentiation, integration, or convolution) on the profile of an impinging wave as it propagates through these blocks. Two approaches are presented to achieve such functionality: (i) subwavelength structured metascreens combined with graded-index waveguides and (ii) multilayered slabs designed to achieve a desired spatial Green's function. Both techniques offer the possibility of miniaturized, potentially integrable, wave-based computing systems that are thinner than conventional lens-based optical signal and data processors by several orders of magnitude.
807 citations
TL;DR: It is demonstrated that by using a simple construction, an acoustically reflecting surface can acquire hybrid resonances and becomes impedance-matched to airborne sound at tunable frequencies, such that no reflection is generated.
Abstract: Acoustic impedance-matched surfaces do not reflect incident waves. Traditional means of acoustic absorption have so far resulted in imperfect impedance matching and bulky structures, or require costly and sophisticated electrical design. Inspired by electromagnetic metamaterials, a subwavelength acoustically reflecting surface with hybrid resonances and impedance-matched to airborne sound at tunable frequencies is now demonstrated.
757 citations
TL;DR: Working with the Miura-ori tessellation, it is found that each unit cell of this crease pattern is mechanically bistable, and by switching between states, the compressive modulus of the overall structure can be rationally and reversibly tuned.
Abstract: Although broadly admired for its aesthetic qualities, the art of origami is now being recognized also as a framework for mechanical metamaterial design. Working with the Miura-ori tessellation, we find that each unit cell of this crease pattern is mechanically bistable, and by switching between states, the compressive modulus of the overall structure can be rationally and reversibly tuned. By virtue of their interactions, these mechanically stable lattice defects also lead to emergent crystallographic structures such as vacancies, dislocations, and grain boundaries. Each of these structures comes from an arrangement of reversible folds, highlighting a connection between mechanical metamaterials and programmable matter. Given origami’s scale-free geometric character, this framework for metamaterial design can be directly transferred to milli-, micro-, and nanometer-size systems.
719 citations
TL;DR: Active metamaterials have been used to realize terahertz imaging with a single-pixel detector Compressive techniques permit high-fidelity images to be acquired at high frame rates as discussed by the authors.
Abstract: Active metamaterials have been used to realize terahertz imaging with a single-pixel detector Compressive techniques permit high-fidelity images to be acquired at high frame rates The technique involves no moving parts and yields improved signal-to-noise ratios over standard raster scanning techniques
695 citations
TL;DR: This Article exploits near-field microscopy to image propagating plasmons in high-quality graphene encapsulated between two films of hexagonal boron nitride (h-BN), and finds unprecedentedly low plasmon damping combined with strong field confinement and confirms the high uniformity of this plAsmonic medium.
Abstract: Graphene plasmons were predicted to possess ultra-strong field confinement and very low damping at the same time, enabling new classes of devices for deep subwavelength metamaterials, single-photon nonlinearities, extraordinarily strong light-matter interactions and nano-optoelectronic switches. While all of these great prospects require low damping, thus far strong plasmon damping was observed, with both impurity scattering and many-body effects in graphene proposed as possible explanations. With the advent of van der Waals heterostructures, new methods have been developed to integrate graphene with other atomically flat materials. In this letter we exploit near-field microscopy to image propagating plasmons in high quality graphene encapsulated between two films of hexagonal boron nitride (h-BN). We determine dispersion and particularly plasmon damping in real space. We find unprecedented low plasmon damping combined with strong field confinement, and identify the main damping channels as intrinsic thermal phonons in the graphene and dielectric losses in the h-BN. The observation and in-depth understanding of low plasmon damping is the key for the development of graphene nano-photonic and nano-optoelectronic devices.
TL;DR: The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction.
Abstract: Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications.
TL;DR: This work demonstrates how metamaterial perfect absorbers can be used to achieve near-unity optical absorption using ultrathin plasmonic nanostructures with thicknesses of 15 nm, smaller than the hot electron diffusion length.
Abstract: While the nonradiative decay of surface plasmons was once thought to be only a parasitic process that limits the performance of plasmonic devices, it has recently been shown that it can be harnessed in the form of hot electrons for use in photocatalysis, photovoltaics, and photodetectors. Unfortunately, the quantum efficiency of hot electron devices remains low due to poor electron injection and in some cases low optical absorption. Here, we demonstrate how metamaterial perfect absorbers can be used to achieve near-unity optical absorption using ultrathin plasmonic nanostructures with thicknesses of 15 nm, smaller than the hot electron diffusion length. By integrating the metamaterial with a silicon substrate, we experimentally demonstrate a broadband and omnidirectional hot electron photodetector with a photoresponsivity that is among the highest yet reported. We also show how the spectral bandwidth and polarization-sensitivity can be manipulated through engineering the geometry of the metamaterial unit ...
TL;DR: By combining the freedom of both the structural design and the orientation of split ring resonator antennas, this work demonstrates terahertz metasurfaces that are capable of controlling both the phase and amplitude profiles over a very broad bandwidth.
Abstract: By combining the freedom of both the structural design and the orientation of split ring resonator antennas, we demonstrate terahertz metasurfaces that are capable of controlling both the phase and amplitude profiles over a very broad bandwidth. As an example, we show that the phase-amplitude metasurfaces can be engineered to control the diffraction orders arbitrarily.
TL;DR: In this paper, a planar terahertz metamaterial was used for ultra-sensitive sensing in the fingerprint region of the tera-hertz regime, where the low-loss quadrupole and Fano resonances with extremely narrow linewidths were used to measure the minute spectral shift caused due to the smallest change in the refractive index of the surrounding media.
Abstract: High quality factor resonances are extremely promising for designing ultra-sensitive refractive index label-free sensors, since it allows intense interaction between electromagnetic waves and the analyte material. Metamaterial and plasmonic sensing have recently attracted a lot of attention due to subwavelength confinement of electromagnetic fields in the resonant structures. However, the excitation of high quality factor resonances in these systems has been a challenge. We excite an order of magnitude higher quality factor resonances in planar terahertz metamaterials that we exploit for ultrasensitive sensing. The low-loss quadrupole and Fano resonances with extremely narrow linewidths enable us to measure the minute spectral shift caused due to the smallest change in the refractive index of the surrounding media. We achieve sensitivity levels of 7.75 × 103 nm/refractive index unit (RIU) with quadrupole and 5.7 × 104 nm/RIU with the Fano resonances which could be further enhanced by using thinner substrates. These findings would facilitate the design of ultrasensitive real time chemical and biomolecular sensors in the fingerprint region of the terahertz regime.
TL;DR: The proposed structures can act as ultrathin highly nonlinear optical elements that enable efficient frequency mixing with relaxed phase-matching conditions, ideal for realizing broadband frequency up- and down-conversions, phase conjugation and all-optical control and tunability over a surface.
Abstract: Intersubband transitions in n-doped multi-quantum-well semiconductor heterostructures make it possible to engineer one of the largest known nonlinear optical responses in condensed matter systems--but this nonlinear response is limited to light with electric field polarized normal to the semiconductor layers. In a different context, plasmonic metasurfaces (thin conductor-dielectric composite materials) have been proposed as a way of strongly enhancing light-matter interaction and realizing ultrathin planarized devices with exotic wave properties. Here we propose and experimentally realize metasurfaces with a record-high nonlinear response based on the coupling of electromagnetic modes in plasmonic metasurfaces with quantum-engineered electronic intersubband transitions in semiconductor heterostructures. We show that it is possible to engineer almost any element of the nonlinear susceptibility tensor of these structures, and we experimentally verify this concept by realizing a 400-nm-thick metasurface with nonlinear susceptibility of greater than 5 × 10(4) picometres per volt for second harmonic generation at a wavelength of about 8 micrometres under normal incidence. This susceptibility is many orders of magnitude larger than any second-order nonlinear response in optical metasurfaces measured so far. The proposed structures can act as ultrathin highly nonlinear optical elements that enable efficient frequency mixing with relaxed phase-matching conditions, ideal for realizing broadband frequency up- and down-conversions, phase conjugation and all-optical control and tunability over a surface.
TL;DR: This topical review addresses materials with a periodic modulation of magnetic parameters that give rise to artificially tailored band structures and allow unprecedented control of spin waves in microand nanostructured ferromagnetic materials.
Abstract: Research efforts addressing spin waves (magnons) in micro- and nanostructured ferromagnetic materials have increased tremendously in recent years. Corresponding experimental and theoretical work in magnonics faces significant challenges in that spin-wave dispersion relations are highly anisotropic and different magnetic states might be realized via, for example, the magnetic field history. At the same time, these features offer novel opportunities for wave control in solids going beyond photonics and plasmonics. In this topical review we address materials with a periodic modulation of magnetic parameters that give rise to artificially tailored band structures and allow unprecedented control of spin waves. In particular, we discuss recent achievements and perspectives of reconfigurable magnonic devices for which band structures can be reprogrammed during operation. Such characteristics might be useful for multifunctional microwave and logic devices operating over a broad frequency regime on either the macro- or nanoscale.
TL;DR: In this article, a metamaterial-inspired microwave microfluidic sensor is proposed, where the main part of the device is a microstrip coupled complementary split-ring resonator (CSRR), and the liquid sample flowing inside the channel modifies the resonance frequency and peak attenuation of the CSRR resonance.
Abstract: A new metamaterial-inspired microwave microfluidic sensor is proposed in this paper. The main part of the device is a microstrip coupled complementary split-ring resonator (CSRR). At resonance, a strong electric field will be established along the sides of CSRR producing a very sensitive area to a change in the nearby dielectric material. A micro-channel is positioned over this area for microfluidic sensing. The liquid sample flowing inside the channel modifies the resonance frequency and peak attenuation of the CSRR resonance. The dielectric properties of the liquid sample can be estimated by establishing an empirical relation between the resonance characteristics and the sample complex permittivity. The designed microfluidic sensor requires a very small amount of sample for testing since the cross-sectional area of the sensing channel is over five orders of magnitude smaller than the square of the wavelength. The proposed microfluidic sensing concept is compatible with lab-on-a-chip platforms owing to its compactness.
TL;DR: The design and experimental characterization of an almost perfect three-dimensional, broadband, and, most importantly, omnidirectional acoustic device that renders a region of space three wavelengths in diameter invisible to sound.
Abstract: The control of sound propagation and reflection has always been the goal of engineers involved in the design of acoustic systems A recent design approach based on coordinate transformations, which is applicable to many physical systems, together with the development of a new class of engineered materials called metamaterials, has opened the road to the unconstrained control of sound However, the ideal material parameters prescribed by this methodology are complex and challenging to obtain experimentally, even using metamaterial design approaches Not surprisingly, experimental demonstration of devices obtained using transformation acoustics is difficult, and has been implemented only in two-dimensional configurations Here, we demonstrate the design and experimental characterization of an almost perfect three-dimensional, broadband, and, most importantly, omnidirectional acoustic device that renders a region of space three wavelengths in diameter invisible to sound
TL;DR: A new class of tunable and switchable acoustic metamaterials comprising resonating units dispersed into an elastic matrix, whose buckling is intentionally exploited as a novel and effective approach to control the propagation of elastic waves.
Abstract: A novel type of acoustic metamaterial made of rubber and metal absorbs or transmits sound waves depending on how the material is squeezed.
TL;DR: An elastic metamaterial with chiral microstructure made of a single-phase solid material that aims to achieve subwavelength negative refraction of elastic waves and may be used as a flat lens for elastic wave focusing.
Abstract: Negative refraction of elastic waves has been studied and experimentally demonstrated in three- and two-dimensional phononic crystals, but Bragg scattering is impractical for low-frequency wave control because of the need to scale the structures to manageable sizes. Here we present an elastic metamaterial with chiral microstructure made of a single-phase solid material that aims to achieve subwavelength negative refraction of elastic waves. Both negative effective mass density and modulus are observed owing to simultaneous translational and rotational resonances. We experimentally demonstrate negative refraction of the longitudinal elastic wave at the deep-subwavelength scale in the metamaterial fabricated in a stainless steel plate. The experimental measurements are in good agreement with numerical simulations. Moreover, wave mode conversion related with negative refraction is revealed and discussed. The proposed elastic metamaterial may thus be used as a flat lens for elastic wave focusing.
TL;DR: 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.
Abstract: 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.
TL;DR: The photonic analogue of topological insulator is experimentally realized by embedding non-bianisotropic and non-resonant metacrystal into a waveguide and the topologically non-trivial bandgap is confirmed by experimentally measured transmission spectra and calculated non-zero spin Chern numbers.
Abstract: Photonic analogue of topological insulator was recently predicted by arranging e/μ (permittivity/permeability)-matched bianisotropic metamaterials into two-dimensional superlattices. However, the experimental observation of such photonic topological insulator is challenging as bianisotropic metamaterial is usually highly dispersive, so that the e/μ-matching condition can only be satisfied in a narrow frequency range. Here we experimentally realize a photonic topological insulator by embedding non-bianisotropic and non-resonant metacrystal into a waveguide. The cross coupling between transverse electric and transverse magnetic modes exists in metacrystal waveguide. Using this approach, the e/μ-matching condition is satisfied in a broad frequency range which facilitates experimental observation. The topologically non-trivial bandgap is confirmed by experimentally measured transmission spectra and calculated non-zero spin Chern numbers. Gapless spin-filtered edge states are demonstrated experimentally by measuring the magnitude and phase of the fields. The transport robustness of the edge states is also observed when an obstacle was introduced near the edge.
TL;DR: This work designs an approximate elasto-mechanical core-shell 'unfeelability' cloak based on pentamode metamaterials and quasi-statically deform cloak and control samples in the linear regime and map the displacement fields by autocorrelation-based analysis of recorded movies.
Abstract: Cloaking of a range of stimuli have been demonstrated in various metamaterials recently. Here, the authors report mechanical cloaking in a pentamode structure, leading to ‘unfeelability’ of a core in an elasto-mechanical core-shell system.
TL;DR: In this article, a series of plasmonic and metamaterial structures can work as efficient narrowband absorbers due to the excitation of plasmic or photonic resonances, providing a great potential for applications in designing selective thermal emitters, biosensing, etc.
Abstract: Electromagnetic absorbers have drawn increasing attention in many areas. A series of plasmonic and metamaterial structures can work as efficient narrowband absorbers due to the excitation of plasmonic or photonic resonances, providing a great potential for applications in designing selective thermal emitters, biosensing, etc. In other applications such as solar-energy harvesting and photonic detection, the bandwidth of light absorbers is required to be quite broad. Under such a background, a variety of mechanisms of broadband/multiband absorption have been proposed, such as mixing multiple resonances together, exciting phase resonances, slowing down light by anisotropic metamaterials, employing high loss materials and so on.
TL;DR: A unified view of practical approaches to achievehyperbolic dispersion using thin film and nanowire structures is presented and the concepts central to the theory of hyperbolic media as well as nanofabrication and characterization details essential to experimentalists are introduced.
Abstract: Metamaterials are nano-engineered media with designed properties beyond those available in nature with applications in all aspects of materials science. In particular, metamaterials have shown promise for next generation optical materials with electromagnetic responses that cannot be obtained from conventional media. We review the fundamental properties of metamaterials with hyperbolic dispersion and present the various applications where such media offer potential for transformative impact. These artificial materials support unique bulk electromagnetic states which can tailor light-matter interaction at the nanoscale. We present a unified view of practical approaches to achieve hyperbolic dispersion using thin film and nanowire structures. We also review current research in the field of hyperbolic metamaterials such as sub-wavelength imaging and broadband photonic density of states engineering. The review introduces the concepts central to the theory of hyperbolic media as well as nanofabrication and characterization details essential to experimentalists. Finally, we outline the challenges in the area and offer a set of directions for future work.
TL;DR: A soft mechanism model is introduced which captures the programmable mechanics, and a general design strategy for confined mechanical metamaterials is outlined, showing how inhomogeneous confinement can be explored to create multistability and giant hysteresis.
Abstract: We create mechanical metamaterials whose response to uniaxial compression can be programmed by lateral confinement, allowing monotonic, nonmonotonic, and hysteretic behavior. These functionalities arise from a broken rotational symmetry which causes highly nonlinear coupling of deformations along the two primary axes of these metamaterials. We introduce a soft mechanism model which captures the programmable mechanics, and outline a general design strategy for confined mechanical metamaterials. Finally, we show how inhomogeneous confinement can be explored to create multistability and giant hysteresis.
TL;DR: By nanopatterning ahyperbolic metamaterial made of Ag and Si multilayers, the spontaneous emission rate of rhodamine dye molecules is enhanced 76-fold at tunable frequencies and the emission intensity of the dye increases by ~80-fold compared with the same hyperbolic meetamaterial without nanostructuring.
Abstract: The spontaneous emission rate and emission intensity of dye molecules are significantly enhanced by using a nanopatterned multilayer hyperbolic metamaterial.
TL;DR: Silicon-process compatible metasurface was designed and tested in the infrared wavelength range and shows promise for sensing applications as well as spectrally selective CP thermal emitters.
Abstract: Metamaterials and metasurfaces represent a remarkably versatile platform for light manipulation, biological and chemical sensing, and nonlinear optics Many of these applications rely on the resonant nature of metamaterials, which is the basis for extreme spectrally selective concentration of optical energy in the near field In addition, metamaterial-based optical devices lend themselves to considerable miniaturization because of their subwavelength features This additional advantage sets metamaterials apart from their predecessors, photonic crystals, which achieve spectral selectivity through their long-range periodicity Unfortunately, spectral selectivity of the overwhelming majority of metamaterials that are made of metals is severely limited by high plasmonic losses Here we propose and demonstrate Fano-resonant all-dielectric metasurfaces supporting optical resonances with quality factors Q>100 that are based on CMOS-compatible materials: silicon and its oxide We also demonstrate that these infrared metasurfaces exhibit extreme planar chirality, opening exciting possibilities for efficient ultrathin circular polarizers and narrow-band thermal emitters of circularly polarized radiation
Posted Content•
TL;DR: A series of plasmonic and metamaterial structures can work as efficient narrow band absorbers, providing a great potential for applications in designing selective thermal emitters, bio-sensing, etc as mentioned in this paper.
Abstract: Electromagnetic absorbers have drawn increasing attention in many areas. A series of plasmonic and metamaterial structures can work as efficient narrow band absorbers due to the excitation of plasmonic or photonic resonances, providing a great potential for applications in designing selective thermal emitters, bio-sensing, etc. In other applications such as solar energy harvesting and photonic detection, the bandwidth of light absorbers is required to be quite broad. Under such a background, a variety of mechanisms of broadband/multiband absorption have been proposed, such as mixing multiple resonances together, exciting phase resonances, slowing down light by anisotropic metamaterials, employing high loss materials and so on.