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1

Consequences of Unit Cell Design in Metamaterial Perfect Absorbers

100%

Bagci F., Akaoglu B.

Acta Physica Polonica A

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2016

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vol. 129

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issue 4

792-796

EN

Metamaterials are a new class of composite materials with unusual properties that allow controlling of electromagnetic waves by properly engineering the response functions, which are not observed in constituent materials. However, since absorption of metamaterials is mainly based on electromagnetic resonances, the operating bandwidth is relatively narrow. Utilization of more than a single metallic structure with different geometrical parameters in each unit cell is a common way of accomplishing multiple band and/or broadband absorption. There are two usual approaches for this purpose: (a) multilayer unit cell design where metallic structures on dielectric substrate are stacked one on top of the other; (b) side by side unit cell design where metallic structures are distributed on a dielectric substrate. However, to the best of our knowledge, these two different approaches are not comparatively investigated. In this study, we propose metamaterial-based perfect absorbers with two different unit cell designs and simulate transmittances, reflectances and absorbances for each design by a commercial electromagnetic solver, CST Microwave Studio. It is found that each design has its own advantages in terms of device thickness, absorption bandwidth and angular dependence, which might be severely important for particular purposes.

2

A Study of Chirality in Gold Nanostructures with Second Harmonic Generation

80%

Valev V., Silhanek A., Gillijns W., Moshchalkov V., Verbiest T.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

498-500

EN

We present the second harmonic generation - circular dichroism response from G-shaped gold nanostructures for P-polarized incoming light. By eliminating the contributions of anisotropy to the signal, an absolute measure of the second harmonic generation - circular dichroism is presented. The system of planar nanostructures is an excellent model for studying the correlation between optical properties and chiral morphology at the nanoscale. Samples with both enantiomorphs of the chiral pattern were prepared and, demonstrating the unambiguous presence of chirality, the second harmonic generation - circular dichroism response from two such samples was fitted simultaneously with a single set of fitting parameters.

3

New Type of Composite Gyrotropic Metamaterial

80%

Paśko W., Zięba P., Tralle I., Çoruh A.

Acta Physica Polonica A

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2017

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vol. 132

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issue 1

121-123

EN

In this work we examined the possibility of fabricating the metamaterial in a relatively simple way. Our idea was to use the three-component mixture of ingredients, where one of them is responsible for the negative permeability μ(ω) of hypothetical metamaterial, while the other two cause the negative value of effective permittivity ε(ω). In our previous work, we considered Hg_{1-x}Cd_xTe semiconductor compound as one of the ingredients of mixture. As fabrication of the Hg_{1-x}Cd_xTe is related to using mercury which is very poisoning, we tried to exclude this material. In the work we proved by numerical simulations the possibility of substituting mercury cadmium telluride by Pb_{1-x}Sn_xTe. We have shown by computer simulations that by the proper fitting of the parameters, e.g. the radius of nanoparticles, their magnetic moments, the relative concentration of ingredients, etc., it is possible to obtain the metamaterial with negative refraction index in a relatively broad range of temperatures and magnetic fields. The last seems to be very promising in terms of practical applications of metamaterials.

4

Vacuum Fluctuations in Optical Metamaterials Containing Nonlinear Dielectrics

70%

Jakšić Z., Ostojić S., Tanasković D., Matović J.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

628-630

EN

We investigated the influence of zero-point fluctuations (vacuum fluctuations, optical quantum noise) to the optical response of electromagnetic metamaterials containing dielectrics with third-order Kerr-like nonlinearity. We determined the zero-point noise and calculated it for different analytes, including those used in forensic analysis and organic pollutants. The zero-point noise level is highest for shortest-wavelength plasmons and decreases towards long-range plasmons. It may be tailored through a convenient design of the metamaterial structure. Since noise spectral power is proportional to the nonlinearity of the analyte species present, we considered the possibility to use zero-point noise as an auxiliary tool for identification of targeted nonlinear samples. We believe that our investigation could be of importance in homeland defence, forensics, biomedicine, etc.

5

Fishnet-Based Metamaterials: Spectral Tuning Through Adsorption Mechanism

70%

Jakšić Z., Tanasković D., Matovic J.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

625-627

EN

In this work we consider the tuning of spectral reflectance of fishnet metamaterials with circular or elliptic apertures due to the presence of dielectric analyte adsorbed within the pores of the dielectric part. We simulated the electromagnetic response of the fishnet metamaterials for the optical range utilizing the finite element method. Our investigation is dedicated to ultrathin, freestanding laminated structures (metal-dielectric-metal self-supported nanomembrane sandwiches with nanometric thickness). We also investigated some issues connected with experimental fabrication of the freestanding fishnets for adsorbtion-based sensors.

6

Bandwidth Improvement for Compact Microstrip Patch Antenna Using Metamaterials

61%

Bougoutaia T., Khedrouche D., Hocini A.

Acta Physica Polonica A

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2016

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vol. 129

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issue 4

538-540

EN

An improved ultra-wideband (UWB) and high gain rectangular microstrip antenna is specifically designed in this paper using planar metamaterial based on double-ring resonators (DRR). The antenna has three double-ring resonators (DRRs) etched on the metal patch, and a partial ground plane so that the impedance matching characteristics of the antenna are much better. The -10 dB impedance bandwidth of the proposed antenna is 2.33-16.96 GHz. The antenna is promising for many applications such as WiMAX (2500-2690 MHz), Bluetooth (2400-2480 MHz) and UWB (3.1-10.7 GHz) applications. In addition, the proposed antenna has an average gain of 4.24 dB and a peak gain of 6.87 dB at 12.2 GHz.

7

Hall Effect in ZnO Extrinsic Structure

61%

Dolník B., Kurimský J., Marton K., Kolcun M., Tomčo L., Briančin J., Fabián M., Halama M., Vojtko M., Rajňák M.

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vol. 126

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issue 1

76-77

EN

Zinc oxide-based extrinsic composite was investigated. The sample was selected from a series of components of one production batch, prepared by standard sintering technology. The content of extrinsic elements in ZnO base was determined by SEM. Van der Pauw method with four-point electrode fixture was used for study of conducting phenomena in square-shaped sample. It is normaly preferred to assume the symmetric uniformity of the electrical properties of sample, for which sheet resistance, bulk resistivity and Hall mobility, sheet carrier density and carrier concentration can be calculated. When the uniformity of measured parameters is breached, the anisotropy in the arrangement of the internal structure may be the cause. There remains the question of whether the extrinsic ZnO material can be isotropic, regarding the electrical conductivity. Although the Hall effect has been measured, preliminary measurements indicate the presence of anisotropy in the measured samples. Before measurement the following phenomena should be taken into account: magneto-electric effect, photo-electric effect and the isothermal condition should be preserved. Paper discusses the uniformity deviations for the defined setup configurations for positive and negative magnetic field directions. Bulk resistivity has been calculated by numerical solution of van der Pauw equation. Large offset voltage during the measurement is discussed.

Refine search results

Consequences of Unit Cell Design in Metamaterial Perfect Absorbers

A Study of Chirality in Gold Nanostructures with Second Harmonic Generation

New Type of Composite Gyrotropic Metamaterial

Vacuum Fluctuations in Optical Metamaterials Containing Nonlinear Dielectrics

Fishnet-Based Metamaterials: Spectral Tuning Through Adsorption Mechanism

Bandwidth Improvement for Compact Microstrip Patch Antenna Using Metamaterials

Hall Effect in ZnO Extrinsic Structure