1,720,972 research outputs found
Design and Fabrication of Nanostructures for Plasmonic Focusing
Full text linkPlasmonic structures have known an increasing interest in the realization of miniaturized devices for light manipulation at subwavelenght scales. New plasmonic phenomena like extraordinary transmission of light and adiabatic nanofocusing opened up to a wide range of promising applications, from biosensing to spectroscopy and imaging. This work is aimed to the design and fabrication of plasmonic nanostructures for plasmon concentration. Two main configurations are proposed, both of them proved to support Surface Plasmon Polaritons (SPP) resonances and allowing light concentration. 1D metallic gratings allow the extraordinary transmission of light and SPP concentration inside subwavelenght slits, while tapered metallic waveguides, thanks to the adiabatic compression of a travelling SPP wave, allow the formation of high intense electromagnetic field hot spots in nanometric volumes (well below the diffraction limit) on the tip of the waveguide. A complete study of the problem, based on a chain process consisting of simulation-nanofabrication-characterization provides an exhaustive investigation into the physics of surface plasmon confinement and its innovative and original applications for Raman spectroscopy, biosensing and subwavelength energy confinement. Different optical setups are proposed and investigated both theoretically and experimentally, from far field measures to near field detection schemes, even with the use of novel input sources, like light possessing orbital angular momentum
Nanofocusing on circularly distributed tapered metallic waveguides by means of plasmonic vortex lenses
No full textWe report our experimental results on the nanofocusing effect at the apex of planar nanotips placed at the center of a plasmonic vortex lens (PVL). PVLs are helical gratings that are able to generate surface plasmon polaritons (SPPs) carrying orbital angular momentum. A specific design allows us to couple the PVL with nanostructures placed at its center. The proposed configuration allows a simultaneous nanofocusing
effect on four facing planar nanotips, showing efficient condensation of SPPs at the metal–air interface toward the end point of the tips. An optimized fabrication process allows us to prepare high-quality structures
with a sharp tip apex. Near-field scanning optical microscopy has been used to demonstrate the nanofocusing effect
Polarization independence of extraordinary transmission trough 1D metallic gratings
Full text linkExtraordinary optical transmission of 1D metallic gratings is studied. Experimental samples are fabricated by means of Electron Beam Lithography. The optical characterization is focused on far field transmission properties and in particular on polarization dependence of the incident light. A peculiar symmetry in transmission spectra at different polarization angles is shown; this symmetry is studied both experimentally, and numerically with FEM method. A comparison between numerical and experimental data is provided. (C) 2011 Optical Society of Americ
Focusing dynamics on circular distributed tapered metallic waveguides by means of plasmonic vortex lenses
No full textWe investigate the focusing effect on circularly distributed planar tapered plasmonic waveguides by means of three-dimensional (3D) finite elements simulations. The proposed configuration allows nanofocusing on four faced planar nanotips, showing efficient condensation of surface plasmons polaritons (SPPs) at the silver/air interface toward the endpoint of the tips. By means of a plasmonic vortex lens it is possible to illuminate the tips with SPP waves carrying orbital angular momentum (OAM), namely plasmonic vortices. Our 3D simulations show that by acting on the topological charge of the plasmonic vortex the electric field charge distribution at the tips apex can be controlled accordingly to the input electric field phase distribution. The results for three particular OAM values are shown, along with a generalization for arbitrary plasmonic vortex angular momentum values
Advancements in Wearable EEG Technology: Electrode Characterization and Signal Quality Assessment
No full textPlasmonic nanofocusing by means of metal coated dielectric nanowedges
No full textWe report our results on arrays of transparent metal coated wedges for plasmonic nanofocusing. FIB milling and chemical etching were used for the fabrication. FEM simulations were used to design the system. The design, fabrication and characterization of wedge structures are presented. The structure shows plasmonic properties in the optical spectral range, with excitation and propagation of surface plasmon polaritons at the wedge tip. The particular designs proposed allow the condensation of plasmonic waves at the wedge tips leading to the nanofocusing effects
Extraordinary optical transmission in one-dimensional gold gratings: near- and far-field analysis
No full textOne-dimensional arrays of nanoslits fabricated on silicon nitride membranes show extraordinary optical transmission. Optical characterization techniques have been used to characterize the transmission spectra and the near-field optical configuration. Experimental results have been compared with numerical simulations in order to elucidate the different modes of light propagation. Near- and far-field optical distribution is studied as a function of the polarization of light. (c) 2011 Optical Society of Americ
High-Frequency Near-Eye Ground Truth for Event-Based Eye Tracking
Full text linkEvent-based eye tracking is a promising solution for efficient and low-power eye tracking in smart eyewear technologies. However, the novelty of event-based sensors has resulted in a limited number of available datasets, particularly those with eye-level annotations, crucial for algorithm validation and deep-learning training. This paper addresses this gap by presenting an improved version of a popular event-based eye-tracking dataset. We introduce a semi-automatic annotation pipeline specifically designed for event-based data annotation. Additionally, we provide the scientific community with the computed annotations for pupil detection at 200Hz
Nanoporous gold-Application to extraordinary optical transmission of light
No full textThe authors present their work in the preparation of nanoporous gold layers and their patterning with an original procedure preserving the porosity, to obtain the phenomenon of extraordinary transmission of light with a porous material. The design, fabrication, and characterization of nanoslit arrays made with bulk gold and nanoporous gold films are presented and their sensing performances are compared after coating with thiolated organic molecules. Thanks to a greatly enhanced surface-to-volume ratio, nanoporous gold reveals benefits for better reaction efficiency and detection sensitivity. Moreover, plasmonic properties in the near-IR range assure employment in plasmonic devices
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