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[IEEE 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Hong Kong, China (2018.11.5-2018.11.9)] 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Designing thin-film metamaterials by tuning effective ENZ behavior
摘要： Using an effective refractive index calculation, we demonstrate the ability to efficiently tune epsilon-near-zero (ENZ) behavior within compact thin-film stacks. Results show the desired effect of broadening the reflectivity profile and improving absorption for an all-oxide ENZ metamaterial.
关键词： near-zero index,metamaterials,perfect absorption,plasmonic,thin film,ENZ tuning,effective index
更新于2025-09-23 15:22:29
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Initial Investigation for the Fabrication of Hyperbolic Metamaterials Based on Ultra-Thin Au Layers
摘要： In this paper, we will present the fabrication possibilities developed within our group for obtaining multilayer hyperbolic metamaterials (HMMs). The minimum metallic layer thickness reproducibly obtainable with our current technology is down to 6 nm, while the dielectric layer can be as low as 4 nm. During the talk we will present our approach for obtaining Au layers with better optical properties than the standard techniques. This is achievable by using an adhesion layer whose influence of the metallic properties is lower than the one of the classical Cr or Ti adhesion layers. These organic adhesion layers behave as dielectrics and thus do not contribute more to the metallic response. Since the imaginary part of permittivity of these layers is negligible and the real part is very close to the silica one, their contribution to the behaviour of the HMMs is minimal. The optical properties of Au with organic adhesion layers showing a closer to theory response than Au with metallic adhesion layer as well as a possible explanation for this behaviour will be presented. This technique can be further used to obtain metal-dielectric multi-layers that lead to HMMs behaviour. Both fabrication possibilities and optical characterisation will be shown and discussed during the talk.
关键词： Au layers optical properties,hyperbolic metamaterials,ultra-thin Au layers
更新于2025-09-23 15:22:29
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A metamaterials-loaded quarter mode SIW microfluidic sensor for microliter liquid characterization
摘要： In this paper, a two concentric complementary split-ring resonators (CSRRs) loaded quarter mode substrate integrated waveguide (QMSIW) is proposed as a compact microfluidic chemical sensor for liquid characterization, demonstrated by the measurement of distilled (DI) water and ethanol liquid mixtures. The proposed sensor can detect the liquid concentration from the resonance frequency shift caused by the liquid sample flowing inside the microfluidic channel engraved on polydimethylsiloxane (PDMS). Its electrical size is only ?0.25λg. The simulated resonant frequency shifts between DI water and 100% ethanol is 1196 MHz (from 2.620 GHz to 3.816 GHz), while less than 6 μL samples are used. The experimental results have validated the possibility of the application of the proposed microfluidic structure as a chemical sensor.
关键词： micro?uidic sensor,Metamaterials,complementary split-ring resonator (CSRR),chemical sensor,substrate integrated waveguides (SIW)
更新于2025-09-23 15:21:21
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Towards silicon-based metamaterials
摘要： We study periodic lattices of silicon nanorods and introduce the concept of a phase diagram that characterizes a transition between the regimes of photonic crystals and dielectric metamaterials when the lattice spacing and operational wavelength vary. We find the conditions when a hexagonal periodic lattice of silicon nanorods can operate as a metamaterial described by averaged parameters. In general, we reveal that the metamaterial regime can be achieved for dielectric permittivity exceeding the value ε = 14, being commonly available for semiconductors in both visible and near-infrared frequency ranges. Thus, advanced semiconductor technologies can offer a versatile platform for novel designs of all-dielectric Mie-resonant metadevices.
关键词： phase diagram,photonic crystals,dielectric metamaterials,Mie resonances,silicon nanorods
更新于2025-09-23 15:21:21
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Magnetoelectric uniaxial metamaterials as wide-angle polarization-insensitive matching layers
摘要： Antire?ection or impedance matching is a topic that has been extensively researched by the optical and microwave communities over the past century and until today. However, due to the diverging wave impedances of TE (s) and TM (p) polarizations with increasing incident angle, it is impossible to achieve perfect matching simultaneously for both polarizations at varying incidence angles with a single conventional isotropic matching layer. To achieve polarization-insensitive matching at an arbitrary incident angle, we propose a magnetoelectric uniaxial metamaterial layer (MEUML) that is inspired by the perfectly matched layer (PML) concept in computational electromagnetics. Similar to the PML, the MEUML requires speci?c uniaxial permittivity and permeability tensors. However, to simultaneously control both the transversal and longitudinal material parameters is not an easy task. To date, a true PML has not been realized with metamaterials. In this paper, we employ a simple and yet special metamaterial unit cell to achieve such control and synthesize a physical MEUML. The unit cell comprises two parallel metallic rings separated by a holey substrate. The transversal electric and magnetic dipole moments, and the longitudinal capacitive and diamagnetic coupling between the rings are judiciously controlled to achieve the required permittivity and permeability tensors. To aid the MEUML synthesis, we also introduce a technique that can extract the material parameter tensors at any incident angle. We ?rst demonstrate this concept by achieving polarization-insensitive matching of a high-index substrate at 45? with a single subwavelength-thick MEUML. We further adapt the concept to the microwave regime by developing a MEUML-based radome. Exceptional matching performance was obtained both in the simulations and measurements. The re?ectance remains below 5% from normal incidence (0?) to near grazing angle (85?) for both polarizations and over a wide bandwidth. With this unprecedented control of the material parameter tensors, the MEUML concept not only can be applied to impedance matching, but also can be utilized in many exotic applications that require extreme control of the material properties.
关键词： wide-angle,impedance matching,polarization-insensitive,radome,magnetoelectric uniaxial metamaterials
更新于2025-09-23 15:21:21
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A flexible procedure to avoid the boundary materials singularities in 2D transformation-based cloaks
摘要： An out-of-plane coordinate transformation can avoid singular materials in a two-dimensional electromagnetic cloak. Based on numerical simulations of elliptical cylinders, in this paper we show that the use of two different constants to define the out-of-plane stretching can result in anisotropic materials with lower values and yet with a better scattering reduction for a given incident wave direction.
关键词： scattering cross-width,Cloaking,coordinate transformation,electromagnetic metamaterials
更新于2025-09-23 15:21:21
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Aperiodic order induced enhancement of weak nonlocality in multilayered dielectric metamaterials
摘要： Recent studies on fully dielectric multilayered metamaterials have shown that the negligibly small nonlocal effects (spatial dispersion) typically observed in the limit of deeply subwavelength layers may be significantly enhanced by peculiar boundary effects occurring in certain critical parameter regimes. These phenomena, observed so far in periodic and randomly disordered geometries, are manifested as strong differences between the exact optical response of finite-size metamaterial samples and the prediction from conventional effective-theory-medium models based on mixing formulas. Here, with specific focus on the Thue-Morse geometry, we make a first step toward extending the studies above to the middle ground of aperiodically ordered multilayers, lying in between perfect periodicity and disorder. We show that, also for these geometries, there exist critical parameter ranges that favor the buildup of boundary effects leading to strong enhancement of the (otherwise negligibly weak) nonlocality. However, the underlying mechanisms are fundamentally different from those observed in the periodic case and exhibit typical footprints (e.g., fractal gaps, quasilocalized states) that are distinctive of aperiodic order. The outcomes of our study indicate that aperiodic order plays a key role in the buildup of the aforementioned boundary effects and may also find potential applications to optical sensors, absorbers, and lasers.
关键词： absorbers,optical sensors,lasers,Thue-Morse geometry,aperiodic order,multilayered dielectric metamaterials,nonlocality
更新于2025-09-23 15:21:21
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ANALYSIS OF THE NICOLSON-ROSS-WEIR METHOD FOR CHARACTERIZING THE ELECTROMAGNETIC PROPERTIES OF ENGINEERED MATERIALS
摘要： A method for predicting the behavior of the permittivity and permeability of an engineered material by examining the measured S-parameters of a material sample is devised, assuming that the sample is lossless and symmetric. The S-parameter conditions under which the material parameters extracted using the Nicolson-Ross-Weir method may be associated with a lossless homogeneous material are described. Also, the relationship between the signs of the real and imaginary parts of the permittivity and permeability are determined, both when the extracted material parameters are real and when they are complex. In particular, the conditions under which metamaterials exhibit double-negative properties may be predicted from the S-parameters of a metamaterial sample. The relationships between material characteristics and the S-parameters should prove useful when synthesizing materials to have certain desired properties. Examples, both from experiment and simulation, demonstrate that the relationships may be used to understand the behavior of several di?erent categories of engineered materials, even when the materials have appreciable loss.
关键词： S-parameters,engineered materials,permeability,permittivity,metamaterials,Nicolson-Ross-Weir method
更新于2025-09-23 15:21:21
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[Springer Series in Optical Sciences] Fano Resonances in Optics and Microwaves Volume 219 (Physics and Applications) || Storage and Retrieval of Electromagnetic Waves in Metamaterials by Dynamical Control of EIT-Like Effect
摘要： The storage of light is one of the most significant applications of electromagnetically induced transparency (EIT) effects in atomic systems. It is also possible to mimic the EIT effect using artificial media, or metamaterials, which are based on coupled resonators. This chapter focuses on metamaterials that realize the storage and retrieval of electromagnetic waves in the same way as the atomic EIT system. We introduce tunable metamaterials that are loaded with variable capacitors, which realize dynamical modulation of the EIT-like effects and the control of asymmetric spectra unique to the Fano resonance. Experiments are performed to show that electromagnetic waves are stored and released coherently in a multi-layered metamaterial designed for the operation in the microwave region. In addition, we show the frequency conversion of the stored waves and the extension of the storage time using parametric amplification.
关键词： Fano resonance,storage of electromagnetic waves,EIT,Electromagnetically induced transparency,parametric amplification,metamaterials
更新于2025-09-23 15:21:21
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Hierarchically structured metamaterials with simultaneously negative mass density and Young’s modulus by using dynamic homogenization
摘要： We propose one-dimensional hierarchical metamaterials (HMMs) that have simultaneously negative mass density and Young’s modulus in the sense of effective properties. Frequency-dependent effective properties of the HMMs are evaluated by using a dynamic homogenization theory. By considering three necessary conditions for dynamic homogenizability, we verify that our proposed HMMs can have physically meaningful double negativity, whereas the conventional periodic structures cannot. In addition, HMMs yield the broader ranges of the frequency and the effective properties for double negativity due to the large number of geometrical parameters. By exploring all the possible effective properties of HMMs, we discuss whether we can design metamaterials with the opposite sign of material properties in nature, ultimately aiming at perfect impedance matching.
关键词： dynamic homogenization,double negativity,impedance matching,hierarchical metamaterials
更新于2025-09-23 15:21:21