We 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.
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http://dx.doi.org/10.1364/AO.54.001161 | DOI Listing |
Nanophotonics
March 2024
School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK 74078, USA.
Nanophotonics
March 2024
Laboratory of Integrated Opto-Mechanics and Electronics, School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Orbital angular momentum (OAM) existing in the vortex light beam with isolated singularities and spiral phase distribution presents significant applications in optical communications and light-field manipulation. The generation of OAM based on plasmonic metasurfaces is generally limited by the large optical loss and weak tunability of metal materials. Three-dimensional (3D) topological insulators (TIs) with insulating bulk states and topologically protected surface states allow the excitation of surface plasmons with low loss in the high-frequency region.
View Article and Find Full Text PDFElectron Airy beams and electron vortex beams are commonly generated using phase masks that imprint a transverse modulation on the particle wave function. Plasmons sustained by nanostructured conductors facilitate substantial interactions with free electrons, enabling considerable transverse modulation of the electron wave function. Consequently, electron Airy and vortex beams can also be produced through interactions between electrons and structured plasmonic fields.
View Article and Find Full Text PDFNat Commun
November 2024
Department of Applied Physics, Aalto University School of Science, Espoo, Finland.
Photonic modes exhibiting a polarization winding akin to a vortex possess an integer topological charge. Lasing with topological charge 1 or 2 can be realized in periodic lattices of up to six-fold rotational symmetry-higher order charges require symmetries not compatible with any two-dimensional Bravais lattice. Here, we experimentally demonstrate lasing with topological charges as high as -5, +7, -17 and +19 in quasicrystals.
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