| 1. |
- Andrearczyk, Tomasz, et al.
(författare)
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Impact of Bismuth Incorporation into (Ga,Mn)As Dilute Ferromagnetic Semiconductor on Its Magnetic Properties and Magnetoresistance
- 2023
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- The impact of bismuth incorporation into the epitaxial layer of a (Ga,Mn)As dilute ferromagnetic semiconductor on its magnetic and electromagnetic properties is studied in very thin layers of quaternary (Ga,Mn)(Bi,As) compound grown on a GaAs substrate under a compressive misfit strain. An addition of a small atomic fraction of 1% Bi atoms, substituting As atoms in the layer, predominantly enhances the spin-orbit coupling strength in its valence band. The presence of bismuth results in a small decrease in the ferromagnetic Curie temperature and a distinct increase in the coercive fields. On the other hand, the Bi incorporation into the layer strongly enhances the magnitude of negative magnetoresistance without affecting the hole concentration in the layer. The negative magnetoresistance is interpreted in terms of the suppression of weak localization in a magnetic field. Application of the weak-localization theory for two-dimensional ferromagnets by Dugaev et al. to the experimental magnetoresistance results indicates that the decrease in spin-orbit scattering length accounts for the enhanced magnetoresistance in (Ga,Mn)(Bi,As).
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| 2. |
- Andrearczyk, Tomasz, et al.
(författare)
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Remnant magnetoresistance effect at the intersection of two ferromagnetic (Ga,Mn)As nanowires
- 2011
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Ingår i: Physica Status Solidi. B: Basic Research. - : Wiley. - 0370-1972. ; 248:7, s. 1587-1591
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Tidskriftsartikel (refereegranskat)abstract
- Cross-like nanostructures composed of two perpendicular ferromagnetic (Ga,Mn)As nanowires were fabricated using electron-beam lithography patterning. Nanostructures of different orientations with respect to the crystallographic axes of the parent (Ga,Mn)As epitaxial layer were studied. Electrical resistance of individual nanowires as a function of applied magnetic field were investigated at low temperatures. Low-field magnetoresistance (MR) of the nanowires exhibits hysteresis-like behaviour and related remnant resistance in zero magnetic field. These effects are explained in terms of magnetic domain walls (DWs) pinned at the wires intersection, which contribute to the wire resistance. The DW resistivity, which depends on the degree of spin misalignment in the wall, has been determined to be of the order of 1 Omega mu m(2). High-field MR has, in turn, allowed determining the lithography-induced anisotropy field for the nanowires of different crystallographic orientations. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 3. |
- Andrearczyk, Tomasz, et al.
(författare)
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Structural Quality and Magnetotransport Properties of Epitaxial Layers of the (Ga,Mn)(Bi,As) Dilute Magnetic Semiconductor
- 2020
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 13:23, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Structural analysis of epitaxial layers of the (Ga,Mn)(Bi,As) quaternary dilute magnetic semiconductor (DMS), together with investigations of their magnetotransport properties, has been thoroughly performed. The obtained results are compared with those for the reference (Ga,Mn)As layers, grown under similar conditions, with the aim to reveal an impact of Bi incorporation on the properties of this DMS material. Incorporation of Bi into GaAs strongly enhances the spin-orbit coupling strength in this semiconductor, and the same has been expected for the (Ga,Mn)(Bi,As) alloy. In turn, importantly for specific spintronic applications, strong spin-orbit coupling in ferromagnetic systems opens a possibility of directly controlling the direction of magnetization by the electric current. Our investigations, performed with high-resolution X-ray diffractometry and transmission electron microscopy, demonstrate that the (Ga,Mn)(Bi,As) layers of high structural quality and smooth interfaces can be grown by means of the low-temperature molecular-beam epitaxy method, despite a large difference between the sizes of Bi and As atoms. Depending on the applied buffer layer, the DMS layers can be grown under either compressive or tensile misfit strain, which influences their magnetic properties. It is shown that even small 1% Bi content in the layers strongly affects their magnetoelectric properties, such as the coercive field and anisotropic magnetoresistance.
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| 4. |
- Andrearczyk, Tomasz, et al.
(författare)
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Tunable Planar Hall Effect in (Ga,Mn)(Bi,As) Epitaxial Layers
- 2021
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 14:16
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Tidskriftsartikel (refereegranskat)abstract
- We have thoroughly investigated the planar Hall effect (PHE) in the epitaxial layers of the quaternary compound (Ga,Mn)(Bi,As). The addition of a small amount of heavy Bi atoms to the prototype dilute ferromagnetic semiconductor (Ga,Mn)As enhances significantly the spin-orbit coupling strength in its valence band, which essentially modifies certain magnetoelectric properties of the material. Our investigations demonstrate that an addition of just 1% Bi atomic fraction, substituting As atoms in the (Ga,Mn)As crystal lattice, causes an increase in the PHE magnitude by a factor of 2.5. Moreover, Bi incorporation into the layers strongly enhances their coercive fields and uniaxial magneto-crystalline anisotropy between the in-plane < 110 & rang; crystallographic directions in the layers grown under a compressive misfit strain. The displayed two-state behaviour of the PHE resistivity at zero magnetic field, which may be tuned by the control of applied field orientation, could be useful for application in spintronic devices, such as nonvolatile memory elements.
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| 5. |
- Antosiewicz, Tomasz, 1981, et al.
(författare)
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Bi-metal coated aperture SNOM probes
- 2011
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819486608 ; 8070
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Konferensbidrag (refereegranskat)abstract
- Aperture probes of scanning near-field optical microscopes (SNOM) offer resolution which is limited by a sum of the aperture diameter at the tip of a tapered waveguide probe and twice the skin depth in metal used for coating. An increase of resolution requires a decrease of the aperture diameter. However, due to low energy throughput of such probes aperture diameters usually are larger than 50 nm. A groove structure at fiber core-metal coating interface for photon-to-plasmon conversion enhances the energy throughput 5-fold for Al coated probes and 30-fold for Au coated probes due to lower losses in the metal. However, gold coated probes have lower resolution, first due to light coupling from the core to plasmons at the outside of the metal coating, and second due to the skin depth being larger than for Al. Here we report on the impact of a metal bilayer of constant thickness for coating aperture SNOM probes. The purpose of the bilayer of two metals of which the outer one is aluminum and the inner is a noble metal is to assure low losses, hence larger transmission. Using body-of-revolution finite-difference time-domain simulations we analyze properties of probes without corrugations to measure the impact of using a metal bilayer and choose an optimum bi-metal configuration. Additionally we investigate how this type of metalization works in the case of grooved probes.
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| 6. |
- Antosiewicz, Tomasz, 1981, et al.
(författare)
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Magnetic probe for material characterization at optical frequencies
- 2011
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819486608 ; 8070
-
Konferensbidrag (refereegranskat)abstract
- Rapid development of novel, functional metamaterials made of purely dielectric, plasmonic, or composite structures which exhibit tunable optical frequency magnetic responses creates a need for new measurement techniques. We propose a method of actively measuring magnetic responses, i.e. magnetic dispersion, of such metamaterials within a wide range of optical frequencies with a single probe by exciting individual elementary cells within a larger matrix. The probe is made of a tapered optical fiber with a radially corrugated metal coating. It concentrates azimuthally polarized light in the near-field below the apex into a subwavelength size focus of the longitudinal magnetic field component. An incident azimuthally polarized beam propagates in the core until it reaches the metal stripes of constant angular width running parallel to the axis. For a broad frequency range light-to-plasmon coupling is assured as the lattice constant changes with the radius due to constant angular width. Bound plasmonic modes in slits between the metal stripes propagate toward the apex where circular currents in stripes and displacement currents in slits generate a strong longitudinal magnetic field. The energy density of the longitudinal magnetic component in the vicinity of the axis is much stronger than that of all the other components combined, what allows for pure magnetic excitation of magnetic resonances rather than by the electric field. The scattered signal is then measured in the far-field and analyzed.
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| 7. |
- Bartuzi, Damian, et al.
(författare)
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Funnel metadynamics and behavioral studies reveal complex effect of D2AAK1 ligand on anxiety-like processes
- 2022
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Ingår i: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Anxiety is a troublesome symptom for many patients, especially those suffering from schizophrenia. Its regulation involves serotonin receptors, targeted e.g. by antipsychotics or psychedelics such as LSD. 5-HT2A receptors are known for an extremely long LSD residence time, enabling minute doses to exert a long-lasting effect. In this work, we explore the changes in anxiety-like processes induced by the previously reported antipsychotic, D2AAK1. In vivo studies revealed that the effect of D2AAK1 on the anxiety is mediated through serotonin 5-HT1A and 5-HT2A receptors, and that it is time-dependent (anxiogenic after 30 min, anxiolytic after 60 min) and dose-dependent. The funnel metadynamics simulations suggest complicated ligand-5HT(2A)R interactions, involving an allosteric site located under the third extracellular loop, which is a possible explanation of the time-dependency. The binding of D2AAK1 at the allosteric site results in a broader opening of the extracellular receptor entry, possibly altering the binding kinetics of orthosteric ligands.
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| 8. |
- Kaczor, Agnieszka A., et al.
(författare)
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Allosteric Modulators of Dopamine D-2 Receptors for Fine-Tuning of Dopaminergic Neurotransmission in CNS Diseases : Overview, Pharmacology, Structural Aspects and Synthesis
- 2023
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Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 28:1
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Forskningsöversikt (refereegranskat)abstract
- Allosteric modulation of G protein-coupled receptors (GPCRs) is nowadays a hot topic in medicinal chemistry. Allosteric modulators, i.e., compounds which bind in a receptor site topologically distinct from orthosteric sites, exhibit a number of advantages. They are more selective, safer and display a ceiling effect which prevents overdosing. Allosteric modulators of dopamine D-2 receptor are potential drugs against a number of psychiatric and neurological diseases, such as schizophrenia and Parkinson's disease. In this review, an insightful summary of current research on D-2 receptor modulators is presented, ranging from their pharmacology and structural aspects of ligand-receptor interactions to their synthesis.
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| 9. |
- Munkhbat, Battulga, 1988, et al.
(författare)
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Optical Constants of Several Multilayer Transition Metal Dichalcogenides Measured by Spectroscopic Ellipsometry in the 300-1700 nm Range: High Index, Anisotropy, and Hyperbolicity
- 2022
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 9:7, s. 2398-2407
-
Tidskriftsartikel (refereegranskat)abstract
- Transition metal dichalcogenides (TMDs) attract significant attention due to their remarkable optical and excitonic properties. It was understood already in the 1960s and recently rediscovered that many TMDs possess a high refractive index and optical anisotropy, which make them attractive for nanophotonic applications. However, accurate analysis and predictions of nanooptical phenomena require knowledge of dielectric constants along both in- and out-of-plane directions and over a broad spectral range, information that is often inaccessible or incomplete. Here, we present an experimental study of optical constants from several exfoliated TMD multilayers obtained using spectroscopic ellipsometry in the broad range of 300-1700 nm. The specific materials studied include semiconducting WS2, WSe2, MoS2, MoSe2, and MoTe2, as well as in-plane anisotropic ReS2 and WTe2 and metallic TaS2, TaSe2, and NbSe2. The extracted parameters demonstrate a high index (n up to ∼4.84 for MoTe2), significant anisotropy (n∥ - n⊥ ≈ 1.54 for MoTe2), and low absorption in the near-infrared region. Moreover, metallic TMDs show potential for combined plasmonic-dielectric behavior and hyperbolicity, as their plasma frequency occurs at around ∼1000-1300 nm depending on the material. The knowledge of optical constants of these materials opens new experimental and computational possibilities for further development of all-TMD nanophotonics.
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| 10. |
- Ortí, Guillermo, et al.
(författare)
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Graft-versus-Host Disease Prophylaxis with PostTransplantation Cyclophosphamide in Chronic Myeloid Leukemia Patients Undergoing Allogeneic Hematopoietic Cell Transplantation from an Unrelated or Mismatched Related Donor : A Comparative Study from the Chronic Malignancies Working Party of the EBMT (CMWP-EBMT)
- 2024
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Ingår i: Transplantation and Cellular Therapy. - : Elsevier. - 2666-6375 .- 2666-6367. ; 30:1, s. 93.e1-93.e12
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Tidskriftsartikel (refereegranskat)abstract
- Outcomes following allogeneic hematopoietic cell transplantation (allo-HCT) for chronic myeloid leukemia (CML) with post-transplantation cyclophosphamide (PTCy) using an unrelated donor (UD) or a mismatched related donor (MMRD) remain unknown. We report a retrospective comparison of PTCy-based allo-HCT from a UD, non-PTCy allo-HCT from a UD, and PTCy allo-HCT from an MMRD. Inclusion criteria were adult patients with CML undergoing first allo-HCT between 2012 and 2019 from a UD with either PTCy or non-PTCy graft-versus-host disease (GVHD) prophylaxis or from an MMRD using PTCy. The primary endpoint was GVHD-free/relapse-free survival (GRFS). A total of 1341 patients were included (82% in the non-PTCy UD cohort). With a median follow-up of 34.9 months, the 3-year GRFS was 43% in the non-PTCy cohort, 37% in the PTCy-UD cohort, and 39% PTCy-MMRD cohort (P = .15). Multivariable analyses revealed no significant differences among the 3 cohorts in terms of overall survival (OS), progression-free survival, RI, and nonrelapse mortality. Factors independently associated with worse OS in the overall cohort were Karnofsky Performance Status <90 (hazard ratio [HR], 1.86; 95% confidence interval [CI], 1.41 to 2.45; P < .001), older age (HR, 1.24, 95% CI, 1.11 to 1.38; P < .001), and disease stage (compared to chronic phase [CP] 1): blast phase (HR, 2.25; 95% CI, 1.60 to 3.16; P < .001), accelerated phase (HR, 1.63; 95% CI, 1.05 to 2.54; P = .03), and CP >2 (HR, 1.58; 95% CI, 1.15 to 2.17; P = .005). These results suggest that allo-HCT in patients with CML using either a UD or an MMRD with PTCy-based GVHD prophylaxis are feasible transplantation, platforms and that the disease stage at allo-HCT remains a major prognostic factor, highlighting the importance of closely monitoring CML patients and proposing transplantation when indicated when still in CP1.
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| 11. |
- Stefaniuk, T., et al.
(författare)
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Plasmonic lenses with long focal lengths
- 2012
-
Ingår i: International Conference on Transparent Optical Networks. - 2162-7339. - 9781467322270
-
Konferensbidrag (refereegranskat)abstract
- We report on recent progress made in the development of plasmonic nanolenses. These lenses exhibit intensity transmittance close to 80%, focal lengths equal to one or more wavelengths, and foci with full-widths at halfmaximum close to the diffraction limit. We consider lenses in the form of (i) a silver layer with no hole on the optical axis and double-sided concentric corrugations, (ii) a silver layer with no hole on the axis and single-sided corrugations, and (iii) a lens composed of several concentric metallic rings and on-axis stop with external layer of transparent dielectric that integrates all elements. Investigations are carried out using the Finite-Difference Time-Domain method and the Transfer Matrix Method. The nanolenses are diffractive optical elements that concentrate radially polarized Laguerre-Gauss illumination as tightly as high-NA refractive optical systems.
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| 12. |
- Stepnicki, Piotr, et al.
(författare)
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Development and Characterization of Novel Selective, Non-Basic Dopamine D-2 Receptor Antagonists for the Treatment of Schizophrenia
- 2023
-
Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 28:10
-
Tidskriftsartikel (refereegranskat)abstract
- The dopamine D-2 receptor, which belongs to the family of G protein-coupled receptors (GPCR), is an important and well-validated drug target in the field of medicinal chemistry due to its wide distribution, particularly in the central nervous system, and involvement in the pathomechanism of many disorders thereof. Schizophrenia is one of the most frequent diseases associated with disorders in dopaminergic neurotransmission, and in which the D-2 receptor is the main target for the drugs used. In this work, we aimed at discovering new selective D-2 receptor antagonists with potential antipsychotic activity. Twenty-three compounds were synthesized, based on the scaffold represented by the D2AAK2 compound, which was discovered by our group. This compound is an interesting example of a D-2 receptor ligand because of its non-classical binding to this target. Radioligand binding assays and SAR analysis indicated structural modifications of D2AAK2 that are possible to maintain its activity. These findings were further rationalized using molecular modeling. Three active derivatives were identified as D-2 receptor antagonists in cAMP signaling assays, and the selected most active compound 17 was subjected to X-ray studies to investigate its stable conformation in the solid state. Finally, effects of 17 assessed in animal models confirmed its antipsychotic activity in vivo.
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| 13. |
- Wosinski, Tadeusz, et al.
(författare)
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Domain-wall controlled (Ga,Mn)As nanostructures for spintronic applications
- 2013
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Ingår i: Physica E: Low-Dimensional Systems and Nanostructures. - : Elsevier BV. - 1386-9477. ; 51, s. 128-134
-
Tidskriftsartikel (refereegranskat)abstract
- Valence-band structure and magnetic properties, especially magnetic anisotropies, in the (Ga,Mn)As diluted ferromagnetic semiconductor are shortly discussed. Next, magneto-resistive, cross-like nanostructures fabricated by electron-beam lithography patterning and chemical etching from thin (Ga,Mn)As epitaxial layers are described. The nanostructures, composed of two perpendicular nanostripes crossing in the middle of their length, represent four-terminal devices, in which an electric current can be driven through any of the two nanostripes. In these devices, which make use of the patterning-induced magnetic anisotropy, a novel magneto-resistive memory effect related to a rearrangement of magnetic domain walls in the central part of the device, has been demonstrated. The effect consists in that the zerb-field resistance of a nanostripe depends on the direction of previously applied magnetic field. The nanostructures can thus work as two-state devices providing basic elements of nonvolatile memory cells. (C) 2012 Elsevier B.V. All rights reserved.
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| 14. |
- Wrobel, Jan S., et al.
(författare)
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Elastic dipole tensors and relaxation volumes of point defects in concentrated random magnetic Fe-Cr alloys
- 2021
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Ingår i: Computational materials science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 194
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Tidskriftsartikel (refereegranskat)abstract
- Point defects in body-centred cubic Fe, Cr and concentrated random magnetic Fe-Cr are investigated using density functional theory and theory of elasticity. The volume of a substitutional Cr atom in ferromagnetic bcc Fe is approximately 18% larger than the volume of a host Fe atom, whereas the volume of a substitutional Fe atom in antiferromagnetic bcc Cr is 5% smaller than the volume of a host Cr atom. In an alloy, elastic dipole P and relaxation volume omega tensors of vacancies and self-interstitial atom (SIA) defects exhibit large fluctuations, with vacancies having negative and SIA large positive relaxation volumes. Dipole tensors of vacancies are nearly isotropic across the entire alloy composition range, with diagonal elements Pii decreasing as a function of Cr content. Fe-Fe and Fe-Cr SIA dumbbells are more anisotropic than Cr-Cr dumbbells. We find that fluctuations of elastic dipole tensors of SIA defects are primarily associated with the variable crystallographic orientations of the dumbbells. Statistical properties of tensors P and omega are analysed using their principal invariants, suggesting that point defects differ significantly in alloys containing below and above 10% at. Cr. The von Mises stresses caused by dumbbells are notably larger than those caused by vacancies. The relaxation volume of a vacancy depends sensitively on whether it occupies a Fe or a Cr lattice site. A correlation between elastic relaxation volumes and magnetic moments of defects found in this study suggests that magnetism is a significant factor influencing elastic fields of defects in Fe-Cr alloys.
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| 15. |
- Wróbel, P., et al.
(författare)
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Concentrator of magnetic field of light
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819491152 ; 8423
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Konferensbidrag (refereegranskat)abstract
- In the recent decade metamaterials with magnetic permeability different than unity and unusual response to the magnetic field of incident light have been intensively explored. Existence of magnetic artificial materials created an interest in a scanning near-field magnetic microscope for studies of magnetic responses of subwavelength elementary cells of those metamaterials. We present a method of measuring magnetic responses of such elementary cells within a wide range of optical frequencies with single probes of two types. The first type probe is made of a tapered silica fiber with radial metal stripes separated by equidistant slits of constant angular width. The second type probe is similar to metal coated, corrugated, tapered fiber apertured SNOM probe, but in this case corrugations are radially oriented. Both types of probes have internal illumination with azimuthally polarized light. In the near-field they concentrate into a subwavelength spot the longitudinal magnetic field component which is much stronger than the perpendicular electric one.
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| 16. |
- Wróbel, P., et al.
(författare)
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Fabrication of corrugated Ge-doped silica fibers
- 2012
-
Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 20:13, s. 14508-14513
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Tidskriftsartikel (refereegranskat)abstract
- We present a method of fabricating Ge-doped SiO2 fibers with corrugations around their full circumference for a desired length in the longitudinal direction. The procedure comprises three steps: hydrogenation of Ge-doped SiO2 fibers to increase photosensitivity, recording of Bragg gratings with ultraviolet light to achieve modulation of refractive index, and chemical etching. Finite-length, radially corrugated fibers may be used as couplers. Corrugated tapered fibers are used as high energy throughput probes in scanning near-field optical microscopy.
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| 17. |
- Wróbel, P., et al.
(författare)
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Fabrication of corrugated probes for scanning near-field optical microscopy
- 2011
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819486608 ; 8070
-
Konferensbidrag (refereegranskat)abstract
- We present a method of fabricating aperture tapered-fiber metal-coated SNOM probes with a corrugated core surface which assures efficient photon-to-plasmon conversion and thus high energy throughput. High energy throughput allows for a small apex aperture and high resolution. The procedure consists of recording of Bragg grating in the to-be-tapered part of a Ge-doped silica fiber and chemical etching with the Turner method. Bragg gratings are recorded with UV light through nearly sinusoidal phase masks of chosen lattice constants. The refractive index contrast in the Bragg grating differentiates the etch rate of the Ge-doped hydrogenated fiber core in exposed and unexposed parts by about 100 nm/min at room temperature.
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| 18. |
- Wróbel, P., et al.
(författare)
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Optimization of transmission and focusing properties of plasmonic nanolenses
- 2011
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819486608 ; 8070
-
Konferensbidrag (refereegranskat)abstract
- We consider two kinds of plasmonic nanolenses which focus radially polarized Laguerre-Gauss beam into subwavelength spot. The first one is free-standing opaque metal layer with concentric grooves on both sides [Phys. Rev. Lett. 102, 183902 (2009)]. The second has slits instead of grooves thus concentric rings have to be integrated with dielectric matrix. Constructive interference of far-field radiation of SPPs scattered on the back side of the lenses gives subwavelength size foci approaching the Rayleigh resolution limit. We investigate transmission and focusing properties of considered metal structures. Choice of appropriate metal such as silver, gold, copper or aluminum strongly affects transmission. Parameters of surface structure determine efficient photon-plasmon coupling and plasmon scattering phenomenon thus influence both transmission and focusing effect. Finally, the choice of dielectric function of surrounding medium gives another degree of freedom to fulfill momentum matching condition for resonant photon-plasmon interaction. In this paper, taking into account the above parameters, we show an optimization procedure, which leads to high transmission, tight focal spot and large focal length of the considered plasmonic nanolenses.
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| 19. |
- Wróbel, P., et al.
(författare)
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Plasmonic concentrator of magnetic field of light
- 2012
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 112:7
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Tidskriftsartikel (refereegranskat)abstract
- We propose an efficient concentrator of the magnetic component of evanescent field of light for measuring magnetic responses of nanostructures. It is in the form of a tapered fiber probe, which in its final part has corrugations along the angular dimension and is coated with metal except for the aperture at the tip. Internal, azimuthally polarized illumination is concentrated into a subwavelength spot with a strong longitudinal magnetic component H-z. Within the visual range of wavelengths 400-700 nm, the energy density of H-z is up to 50 times larger than that of the azimuthal electric E-phi one. This dominant H-z contribution may be used for magnetic excitation of elementary cells of metamaterials with a single probe guiding a wide spectrum of generated plasmons.
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| 20. |
- Wróbel, P., et al.
(författare)
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Preparation of high energy throughput SNOM probes
- 2011
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Ingår i: 13th International Conference on Transparent Optical Networks, ICTON 2011, Stockholm, 26-30 June 2011. - 2162-7339. - 9781457708800
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Konferensbidrag (refereegranskat)abstract
- In this technical note we present technological steps of fabrication of high energy throughput SNOM probes. The core-metal coating interface of probes is corrugated what enhances photon-to-plasmon coupling. A strong evanescent field allows for reduction of aperture diameter, which together with skin depth of metal used for coating decide upon resolution. Probes are made of Ge-doped silica glass fibre, which is hydrogenated to increase its photosensitivity. A Bragg grating is recorded in the cores with UV light diffracted into +1 st/1st diffraction orders on a sinusoidal phase mask. Modulation of the refractive index is connected with different etch rates. Etching with the Turner method is made in aqueous solution of HF acid. A corrugated tapered fibre is then coated with aluminium in a special rotating holder. We present results of this novel multi step technology.
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| 21. |
- Zieliński, Tomasz G., et al.
(författare)
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Reproducibility of sound-absorbing periodic porous materials using additive manufacturing technologies : Round robin study
- 2020
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Ingår i: Additive Manufacturing. - : Elsevier B.V.. - 2214-8604 .- 2214-7810. ; 36
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work is to check if additive manufacturing technologies are suitable for reproducing porous samples designed for sound absorption. The work is an inter-laboratory test, in which the production of samples and their acoustic measurements are carried out independently by different laboratories, sharing only the same geometry codes describing agreed periodic cellular designs. Different additive manufacturing technologies and equipment are used to make samples. Although most of the results obtained from measurements performed on samples with the same cellular design are very close, it is shown that some discrepancies are due to shape and surface imperfections, or microporosity, induced by the manufacturing process. The proposed periodic cellular designs can be easily reproduced and are suitable for further benchmarking of additive manufacturing techniques for rapid prototyping of acoustic materials and metamaterials.
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