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[IEEE 2018 IEEE 23rd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD) - Barcelona (2018.9.17-2018.9.19)] 2018 IEEE 23rd International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD) - Towards a Circular Economy via Intelligent Metamaterials
摘要： The present study proposes the use of intelligent metasurfaces in the design of products, as enforcers of circular economy principles. Intelligent metasurfaces can tune their physical properties (electromagnetic, acoustic, mechanical) by receiving software commands. When incorporated within products and spaces they can mitigate the resource waste caused by inefficient, partially optimized designs and security concerns. Thus, circular economy and fast-paced product design become compatible. The study begins by considering electromagnetic metamaterials, and proposes a complete methodology for their deployment. Finally, it is shown that the same principles can be extended to the control of mechanical properties of objects, exemplary enabling the micro-management of vibrations and heat, with unprecedented circular economy potential.
关键词： micro-management,metasurfaces,Circular economy,energy,acoustic,mechanical,material properties,metamaterials,electromagnetic,HyperSurfaces,security
更新于2025-09-09 09:28:46
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Metasurface-Based THz Dual-Band Absorber Sensor for the Measurement of Refractive Index Variations of Chemical and Biological Substances
摘要： In this paper we report on the results of the simulations of the electromagnetic properties of a metasurface composed of a 2D-array of plasmonic nanoantennas acting as polarisation insensitive dual band THz perfect absorber able to achieve absorption coefficients and quality factors up to 99.6% and 122, respectively. The 2D-array is designed on top of a polyimide flexible film separating it from an Ag ground layer. The plasmonic nanoantenna is composed of two Ag quadrangular rings and an Ag diamond-shape dot is placed at their geometrical centre. The absorption resonances show a linear frequency shift with respect to variations of the refractive index of transparent substances adsorbed on the metasurface. This allows the dual-band absorber to be employed as a sensor of the chemical/physical modifications taking place on the substance. In particular, in terms of the refractive index units, the sensor based on the dual-band absorber can achieve sensitivities up to 310 GHz/RIU.
关键词： THz perfect absorber,functionalised metasurfaces,plasmonic sensors
更新于2025-09-09 09:28:46
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Multichannel vectorial holographic display and encryption
摘要： Since its invention, holography has emerged as a powerful tool to fully reconstruct the wavefronts of light including all the fundamental properties (amplitude, phase, polarization, wave vector, and frequency). For exploring the full capability for information storage/display and enhancing the encryption security of metasurface holograms, smart multiplexing techniques together with suitable metasurface designs are highly demanded. Here, we integrate multiple polarization manipulation channels for various spatial phase profiles into a single birefringent vectorial hologram by completely avoiding unwanted cross-talk. Multiple independent target phase profiles with quantified phase relations that can process significantly different information in different polarization states are realized within a single metasurface. For our metasurface holograms, we demonstrate high fidelity, large efficiency, broadband operation, and a total of twelve polarization channels. Such multichannel polarization multiplexing can be used for dynamic vectorial holographic display and can provide triple protection for optical security. The concept is appealing for applications of arbitrary spin to angular momentum conversion and various phase modulation/beam shaping elements.
关键词： metasurfaces,polarization multiplexing,holography,optical encryption,vectorial holography
更新于2025-09-09 09:28:46
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Super-Oscillatory Metalens at Terahertz for Enhanced Focusing with Reduced Side Lobes
摘要： In this paper, we design and numerically demonstrate an ultra-thin super-oscillatory metalens with a resolution below the diffraction limit. The zones of the lens are implemented using metasurface concepts with hexagonal unit cells. This way, the transparency and, hence, ef?ciency is optimized, compared to the conventional transparent–opaque zoning approach that introduces, inevitably, a high re?ection in the opaque regions. Furthermore, a novel two-step optimization technique, based on evolutionary algorithms, is developed to reduce the side lobes and boost the intensity at the focus. After the design process, we demonstrate that the metalens is able to generate a focal spot of 0.46λ0 (1.4 times below the resolution limit) at the design focal length of 10λ0 with reduced side lobes (the side lobe level being approximately ?11 dB). The metalens is optimized at 0.327 THz, and has been validated with numerical simulations.
关键词： metamaterials,evolutionary algorithm,metasurfaces,terahertz,metalens,terahertz focusing,subwavelength focusing,super-oscillatory lens
更新于2025-09-09 09:28:46
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Tunability methods for magnetic resonance imaging applications of metasurfaces
摘要： In this work, we propose and discuss methods of tuning eigenmode resonance frequencies of wire metasurfaces. Fine tuning of metasurface properties is essential for maximizing its coupling with transmitting and receiving radiofrequency (RF) coils of a magnetic resonance imaging (MRI) system. We have studied numerically and experimentally two designs of metasurfaces with different tunability mechanisms. The first design is a hybrid structure based on periodic wires with extremities penetrating high-permittivity dielectric volumes, where tunability achieved by changing properties of the dielectric parts. The second metasurface is formed by an array of capacitively loaded telescopic wires that permit to adjust the eigenmode resonance frequencies by mechanical expansion of the wires. Both metasurfaces demonstrated the spectacular capability to locally enhance the magnetic field of an external RF coil being precisely tuned to the Larmor frequency of a clinical MRI scanner.
关键词： metasurfaces,RF coils,tunability,eigenmode resonance frequencies,magnetic resonance imaging
更新于2025-09-09 09:28:46
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Meta-optics and bound states in the continuum
摘要： We discuss the recent advances in meta-optics and nanophotonics associated with the physics of bound states in the continuum (BICs). Such resonant states appear due to a strong coupling between leaky modes in optical guiding structures being supported by subwavelength high-index dielectric Mie-resonant nanoantennas or all-dielectric metasurfaces. First, we review brie?y very recent developments in the BIC physics in application to isolated subwavelength particles. We pay a special attention to novel opportunities for nonlinear nanophotonics due to the large ?eld enhancement inside the particle volume creating the resonant states with high-quality (high-Q) factors, the so-called quasi-BIC, that can be supported by the subwavelength particles. Second, we discuss novel applications of the BIC physics to all-dielectric optical metasurfaces with broken-symmetry meta-atoms when tuning to the BIC conditions allows to enhance substantially the Q factor of the ?at-optics dielectric structures. We also present the original results on nonlinear high-Q metasurfaces and predict that the frequency conversion ef?ciency can be boosted dramatically by smart engineering of the asymmetry parameter of dielectric metasurfaces in the vicinity of the quasi-BIC regime.
关键词： bound states in the continuum,high-Q resonances,nanophotonics,nonlinear nanophotonics,BICs,dielectric metasurfaces,meta-optics
更新于2025-09-09 09:28:46
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Metasurfaces for independent manipulation of the wavefronts in the different states of phase change materials
摘要： Metasurfaces have attracted increasing attention due to their extraordinary capability in the arbitrary control of electromagnetic waves. However, most metasurfaces lack flexibility and only enable fixed optical performance once fabricated. In this work, we propose ultra-thin metasurfaces with varied functionalities using phase change materials (PCMs) when phase change occurs on whole structured PCMs, which has not been found in previous reports. The wavefronts in the amorphous and crystalline states of the PCMs can be arbitrarily and independently modulated with high efficiency (～60% and ～40% in the two states, respectively). This work may be valuable for information encryption and optical communications.
关键词： wavefront manipulation,metasurfaces,information encryption,phase change materials,optical communications
更新于2025-09-09 09:28:46
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Efficient Excitation of a Toroidal Dipole Mode in All-Dielectric Quadrumer Clusters
摘要： We demonstrate a novel design of all-dielectric metasurfaces featuring strong axial toroidal response. A unit cell of the metamaterial is constructed by arranging two types of dielectric disks into an asymmetric quadrumer cluster. The toroidal response is achieved via the excitation of a trapped mode due to the symmetry breaking in the cluster. Dependence of the toroidal response on the degree of asymmetry in the cluster geometry, that appears from the different compositions of holes introduced into the disks, is studied both numerically and experimentally in the microwave regime.
关键词： metasurfaces,frequency selective surfaces,dielectric resonators
更新于2025-09-04 15:30:14
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Total Reflection Metasurface with Pure Modulated Signal
摘要： Metasurface has been proposed as one critical platform for orbital angular momentum (OAM) multiplexing. While metasurfaces have unique advantages to achieve light modulation with an ultrathin 2D layer, the relatively low transfer efficiency is a primary drawback. Such weakness leads to the mixing of unmodulated light into the output signal and greatly limits the functionality. A new design strategy is presented to fabricate self-filtering metasurface with pure signal light, which is computationally and experimentally verified on different applications, and it is also insensitive to the incident light polarization. Normal metasurface system requires bulky polarizer and filter, while our ultrathin design paves the way to multifunctional metasurface-based chip-scale circuits to replace the conventional bulky optical components. A proof-of-principle meta-cavity is designed to improve the transfer efficiency by 83%, while theoretical calculation shows 633% enhancement for an upgraded setup. This design can be widely applied to OAM optics, integrated photonics, optical sensing, data processing, and nanoimaging.
关键词： noise reduction,metasurfaces,nanophotonics,efficiency enhancement
更新于2025-09-04 15:30:14
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Compact Aberration‐Corrected Spectrometers in the Visible Using Dispersion‐Tailored Metasurfaces
摘要： The spectral resolution and range of conventional spectrometers are typically limited by optical aberrations of their focusing elements, mainly due to chromatically induced astigmatism and an intrinsically curved focal plane. Traditional approaches to overcome this challenge require additional optical components which introduce significant bulk and design complexity to the system and prevent easy integration with portable devices. Here a single planar off-axis focusing metalens consisting of subwavelength TiO2 nanofins whose focal spots lie along a plane and undergo minimal focal spot broadening for almost 200 nm across the visible spectrum is demonstrated. This allows us to achieve a miniature aberration-corrected spectrometer with nanometer spectral resolution, while having a beam propagation distance of only 4 cm to the camera plane. This is achieved by dispersion engineering: tailoring the phase, group delay (GD) and GD dispersion of the metalens. This approach is general and can also be used to introduce customized functionalities to the metalens such as a linear dispersion in the frequency domain with minimal additional overhead.
关键词： off-axis lens,spectroscopy,metasurfaces,aberration corrected
更新于2025-09-04 15:30:14