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Content available remote SU-8 based planar metamaterials with fourfold symmetry as selective terahertz absorbers
Grześkiewicz B., Sierakowski A., Marczewski J., Pałka N., Wolarz E.
Opto-Electronics Review
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2018
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Vol. 26, No. 4
329--337
EN
We report on the absorption properties of polarization-insensitive transmissive and reflective metamaterial absorbers based on two planar aluminium periodic structures and SU-8 epoxy resist. These absorbers were investigated using numerical simulation and experimental methods in the terahertz range (below 2 THz). SU-8 is a very promising organic material for dielectric layers in planar metamaterials, because its application simplifies the process of fabricating these structures and significantly reduces the fabri-cation time. The experimental absorption of the metamaterial absorbers has narrowband characteristics that were consistent with the numerical simulations. Power flow analysis in the transmissive metama-terial unit cell shows that the absorption in the terahertz range occurs primarily in the SU-8 layer of the absorber.
2
Content available remote Analiza numeryczna absorberów metamateriałowych dla zakresu terahercowego
Grześkiewicz B., Wolarz E., Ładniak L.
Przegląd Elektrotechniczny
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2013
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R. 89, nr 2a
45--50
PL
Przy użyciu pakietu programów CST Microwave Studio zaprojektowano szereg struktur metamateriałowych realizujących funkcje absorberów terahercowych. Komórka elementarna sieci tych metamateriałów składa się z elementów metalowych położonych na dwóch równoległych powierzchniach, oddzielonych warstwą dielektryka, wykonanych na podłożu z wysokorezystywnego krzemu. Symulacje numeryczne pozwoliły wyznaczyć współczynniki transmisji i odbicia fal elektromagnetycznych na granicy ośrodka metamateriałowego i próżni oraz absorpcję promieniowania terahercowego przez strukturę metamateriałową w funkcji częstotliwości. Analiza numeryczna potwierdziła występowanie silnej, selektywnej absorpcji promieniowania terahercowego przez zaprojektowane metamateriały. Przeprowadzono również analizę oddziaływań fal terahercowych z rozważanymi metamateriałami posługując się modelem linii transmisyjnej.
EN
Using CST Microwave Studio programming package, a series of structures performing the functions of terahertz metamaterial absorbers were designed. A unit cell of such metamaterials consists of two-layer metal structures, separated by a thin layer of dielectric material, deposited on the substrate of high-resistive silicon. The simulations allowed the determination of transmission, reflection and absorption parameters for electromagnetic waves on the boundary between metamaterial medium and vacuum as a function of frequency. Numerical analysis confirmed the presence of a strong, selective absorption of terahertz radiation by designed metamaterials. The analysis of the interaction of terahertz radiation with the considered metamaterials based on the equivalent transmission line model was also done.
3
Content available remote Dielectric and orientational properties of nematogenic 4-n-octyl(4'-cyanophenyl)benzoate
Bauman D., Jadżyn J., Wolarz E., Modlińska A., Dąbrowski R.
Opto-Electronics Review
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2010
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Vol. 18, No. 1
63-70
EN
Experimental studies of the dielectric properties in the nematic and isotropic phases of 4-cyanophenyl-4'-n-octylbenzoate (8CPB) have been performed in the frequency range from 50 kHz to 100 MHz. The relaxation process related to the rotation around the short molecular axis has been analysed. The results obtained have revealed that in the vicinity of the I-N phase transition, the molecular subdiffusional rotation process occurs. It is connected with the pretransitional effects which are observed both in the static and dynamic dielectric measurements. On the basis of the temperature dependence of the relaxation time in the nematic and isotropic phases, the orientational order parameter < P2 > has been determined. The values of < P2 > obtained in this way have been compared with those evaluated from the measurements of the polarized electronic absorption of the dichroic dye, dissolved as guest probe in the mesogenic host.
4
Content available remote Spectral and orientational properties of new group of naphthalene derivatives of bicarboxylic acid in liquid crystal 7CB
Bielejewska N., Wolarz E., Stolarski R., Bauman D.
Opto-Electronics Review
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2008
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Vol. 16, No. 4
367-374
EN
The spectral and orientational properties of some dichroic fluorescent dyes (naphthalene derivatives of bicarboxylic acid) in some isotropic solvents and in an anisotropic matrix have been studied. The order parameter of the dyes in the nematogenic liquid crystal 7CB has been determined from measurements of polarized electronic absorption and fluorescence. The influence of the dye addition on the nematic-isotropic phase transition temperature of 7CB has been investigated. It was found that some of the dyes studied could be successfully utilized in guest-host liquid crystal display devices.
5
Content available remote Metamateriały - nowe zastosowania elektrodynamiki
Wolarz E.
Postępy Fizyki
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2007
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T. 58, z. 6
242-249
EN
Artificial structures composed of metalic cylinders, rings, squares, and wires present unusual electromagnetic properties which are not found in natural materials.
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