Application of cylindrical IE-GSTC to physical metasurfaces

<div>This work validates cylindrical IE-GSTC by applying it to physical metasurfaces, i.e. metasurfaces defined by material properties and dimensions rather than by susceptibility tensor components. Previously reported IE-GSTC which was formulated for zero thickness GSTC discontinuity is extended to handle finite thickness of physical metasurfaces. A simple analytical approach is used to extract the bianisotropic susceptibility tensor of concentric, multilayered, magneto-dielectric shell. Plane wave scattering by a physical metasurface constructed of four segments of multilayered, magneto-dielectric metasurface scatterers is used as an example problem to validate cylindrical IEGSTC. A second example considers an opening on the cylindrical metasurface, confirming IE-GSTC can handle metasurfaces with openings. Good agreement is obtained between IE-GSTC results and full wave simulation results for both cases.</div>

Application of cylindrical IE-GSTC to physical metasurfaces

<div>This work validates cylindrical IE-GSTC by applying it to physical metasurfaces, i.e. metasurfaces defined by material properties and dimensions rather than by susceptibility tensor components. Previously reported IE-GSTC which was formulated for zero thickness GSTC discontinuity is extended to handle finite thickness of physical metasurfaces. A simple analytical approach is used to extract the bianisotropic susceptibility tensor of concentric, multilayered, magneto-dielectric shell. Plane wave scattering by a physical metasurface constructed of four segments of multilayered, magneto-dielectric metasurface scatterers is used as an example problem to validate cylindrical IEGSTC. A second example considers an opening on the cylindrical metasurface, confirming IE-GSTC can handle metasurfaces with openings. Good agreement is obtained between IE-GSTC results and full wave simulation results for both cases.</div>

Application of cylindrical IE-GSTC to physical metasurfaces

<div>This work validates cylindrical IE-GSTC by applying it to physical metasurfaces, i.e. metasurfaces defined by material properties and dimensions rather than by susceptibility tensor components. Previously reported IE-GSTC which was formulated for zero thickness GSTC discontinuity is extended to handle finite thickness of physical metasurfaces. A simple analytical approach is used to extract the bianisotropic susceptibility tensor of concentric, multilayered, magneto-dielectric shell. Plane wave scattering by a physical metasurface constructed of four segments of multilayered, magneto-dielectric metasurface scatterers is used as an example problem to validate cylindrical IEGSTC. A second example considers an opening on the cylindrical metasurface, confirming IE-GSTC can handle metasurfaces with openings. Good agreement is obtained between IE-GSTC results and full wave simulation results for both cases.</div>

Directivity enhancement of a cylindrical wire antenna by a graded index dielectric shell designed using strictly conformal transformation optics

A transformation-optical method is presented to enhance the directivity of a cylindrical wire antenna by using an all-dielectric graded index medium. The strictly conformal mapping between two doubly connected virtual and physical domains is established numerically. Multiple directive beams are produced, providing directive emission. The state-of-the-art optical path rescaling method is employed to mitigate the superluminal regions. The resulting transformation medium is all-dielectric and nondispersive, which can provide broadband functionality and facilitate the realization of the device using available fabrication technologies. The realization of the device is demonstrated by dielectric perforation based on the effective medium theory. The device’s functionality is verified by carrying out both ray-tracing and full-wave simulations using finite-element-based software COMSOL Multiphysics.

Theoretical and Experimental Study on the Functionalization Effect on the SERS Enhancement Factor of SiO2-Ag Composite Films

Herein we addressed a study to determine the enhancement factor (EF) of the Raman signal reached by composite films with two main components, Ag nanoparticles and SiO2 spheres. The study involves the synthesis, structural composition and optical response by using experimental techniques and theoretical-numerical modeling. A colloid with single NPs and agglomerates of them, with a tannic acid layer on its surface, was produced. Separately, porous SiO2 spheres were obtained. A mixture of both, Ag NPs and SiO2 particles was used to produce the films by solvent evaporation method. It is shown that single or agglomerated Ag NPs are preferentially located at the interstices of the SiO2 spheres. Using discrete dipole approximation, the SERS EF has been estimated considering the agglomeration and tannic acid layer. Both, the dielectric spheres and tannic acid layer diminish the electric field intensity and therefore the SERS EF. When a Ag NP with/without a dielectric shell is touching a SiO2 sphere, the EF is as high as 1 × 103, the zones where this value is reached are smaller when the dielectric layer is present. With a cluster of 3 nude Ag NPs surrounded by SiO2 spheres an EF of 2.4 × 103 is obtained.

Application of cylindrical IE-GSTC to physical metasurfaces

<div>This work validates cylindrical IE-GSTC by applying it to physical metasurfaces, i.e. metasurfaces defined by material properties and dimensions rather than by susceptibility tensor components. Previously reported IE-GSTC which was formulated for zero thickness GSTC discontinuity is extended to handle finite thickness of physical metasurfaces. A simple analytical approach is used to extract the bianisotropic susceptibility tensor of concentric, multilayered, magneto-dielectric shell. Plane wave scattering by a physical metasurface constructed of four segments of multilayered, magneto-dielectric metasurface scatterers is used as an example problem to validate cylindrical IEGSTC. A second example considers an opening on the cylindrical metasurface, confirming IE-GSTC can handle metasurfaces with openings. Good agreement is obtained between IE-GSTC results and full wave simulation results for both cases.</div>

Application of cylindrical IE-GSTC to physical metasurfaces

<div>This work validates cylindrical IE-GSTC by applying it to physical metasurfaces, i.e. metasurfaces defined by material properties and dimensions rather than by susceptibility tensor components. Previously reported IE-GSTC which was formulated for zero thickness GSTC discontinuity is extended to handle finite thickness of physical metasurfaces. A simple analytical approach is used to extract the bianisotropic susceptibility tensor of concentric, multilayered, magneto-dielectric shell. Plane wave scattering by a physical metasurface constructed of four segments of multilayered, magneto-dielectric metasurface scatterers is used as an example problem to validate cylindrical IEGSTC. A second example considers an opening on the cylindrical metasurface, confirming IE-GSTC can handle metasurfaces with openings. Good agreement is obtained between IE-GSTC results and full wave simulation results for both cases.</div>

Linear chains of Ag nanoparticles embedded in dielectric films for SERS applications in analytical chemistry

In line with the SHINERS approach, in which Raman amplification is provided by metallic nanoparticles with an ultrathin dielectric shell, we report on a SERS substrate consisting of lines of Ag nanoparticles embedded in dielectric surfaces.

Gallium chiral nanoshaping for circular polarization handling

Core/shell nanohelices with VIS-CD are grown using FIBID, with the Ga+ source shaping the metallic core and the gas precursor the dielectric shell