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Vento V, Roelli P, Verlekar S, Galland C. Mode-Specific Coupling of Nanoparticle-on-Mirror Cavities with Cylindrical Vector Beams. NANO LETTERS 2023. [PMID: 37205630 DOI: 10.1021/acs.nanolett.3c00561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Nanocavities formed by ultrathin metallic gaps permit the reproducible engineering and enhancement of light-matter interaction, with mode volumes reaching the smallest values allowed by quantum mechanics. While the enhanced vacuum field in metallic nanogaps has been firmly evidenced, fewer experimental reports have examined the far-field to near-field input coupling under strongly focused laser beam. Here, we experimentally demonstrate selective excitation of nanocavity modes controlled by the polarization and frequency of the laser beam. We reveal mode selectivity by recording confocal maps of Raman scattering excited by cylindrical vector beams, which are compared to the known excitation near-field patterns. Our measurements reveal the transverse vs longitudinal polarization of the excited antenna mode and how the input coupling rate depends on laser wavelength. The method introduced here is easily applicable to other experimental scenarios, and our results help connect far-field with near-field parameters in quantitative models of nanocavity-enhanced phenomena.
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Affiliation(s)
- Valeria Vento
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Philippe Roelli
- Nano-optics Group, CIC nanoGUNE, E-20018 Donostia-San Sebastián, Spain
| | - Sachin Verlekar
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Christophe Galland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Tao W, Laible F, Hmima A, Maurer T, Fleischer M. Shape-altering flexible plasmonics of in-situ deformable nanorings. NANO CONVERGENCE 2023; 10:15. [PMID: 36997831 PMCID: PMC10063774 DOI: 10.1186/s40580-023-00358-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 01/29/2023] [Indexed: 06/19/2023]
Abstract
Nanorings (NRs) with their intrinsic cavities have attracted interest as plasmonic nanoparticles for years, due to the uniform electric field enhancement inside the cavity, lower plasmon damping effects and comparatively high refractive index sensitivities. In the present work, we successfully fabricated a series of Au NR arrays on flexible polydimethylsiloxane substrates by taking advantage of state-of-the-art fabrication methods such as electron beam lithography and wet-etching transfer techniques. In-situ optical measurements on these flexible systems are enabled by implementing a homemade micro-stretcher inside an optical reflection spectroscopy setup. The corresponding dark-field spectra of thin-walled NR arrays exhibit a strong shift to longer wavelengths (i.e., ~ 2.85 nm per 1% strain) under polarization perpendicular to the traction, mainly resulting from the increasing shape deformation of the NRs under strain. Moreover, numerical simulations illustrate that the shifting plasmonic mode has a radially-symmetric charge distribution of the bonding mode and is rather sensitive to the tuning of the NRs' shape as confirmed by a subsequent in-situ scanning electron microscope characterization. These results explore the possibilities of shape-altering flexible plasmonics for nanoparticles with a cavity and indicate potential applications for plasmonic colors and biochemical sensing in future work.
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Affiliation(s)
- Wei Tao
- Institute for Applied Physics and Center LISA+, Eberhard Karls University Tübingen, 72076, Tübingen, Germany.
- Laboratory Light, Nanomaterials and Nanotechnologies-L2n, University of Technology of Troyes and CNRS EMR 7004, 12 rue Marie Curie, CS 42060, CEDEX, 10004, Troyes, France.
| | - Florian Laible
- Institute for Applied Physics and Center LISA+, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Abdelhamid Hmima
- Laboratory Light, Nanomaterials and Nanotechnologies-L2n, University of Technology of Troyes and CNRS EMR 7004, 12 rue Marie Curie, CS 42060, CEDEX, 10004, Troyes, France
| | - Thomas Maurer
- Laboratory Light, Nanomaterials and Nanotechnologies-L2n, University of Technology of Troyes and CNRS EMR 7004, 12 rue Marie Curie, CS 42060, CEDEX, 10004, Troyes, France.
| | - Monika Fleischer
- Institute for Applied Physics and Center LISA+, Eberhard Karls University Tübingen, 72076, Tübingen, Germany.
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van den Berg M, Moeinian A, Kobald A, Chen YT, Horneber A, Strehle S, Meixner AJ, Zhang D. Revealing the local crystallinity of single silicon core-shell nanowires using tip-enhanced Raman spectroscopy. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1147-1156. [PMID: 32802717 PMCID: PMC7404174 DOI: 10.3762/bjnano.11.99] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/16/2020] [Indexed: 05/26/2023]
Abstract
Tip-enhanced Raman spectroscopy is combined with polarization angle-resolved spectroscopy to investigate the nanometer-scale structural properties of core-shell silicon nanowires (crystalline Si core and amorphous Si shell), which were synthesized by platinum-catalyzed vapor-liquid-solid growth and silicon overcoating by thermal chemical vapor deposition. Local changes in the fraction of crystallinity in these silicon nanowires are characterized at an optical resolution of about 300 nm. Furthermore, we are able to resolve the variations in the intensity ratios of the Raman peaks of crystalline Si and amorphous Si by applying tip-enhanced Raman spectroscopy, at sample positions being 8 nm apart. The local crystallinity revealed using confocal Raman spectroscopy and tip-enhanced Raman spectroscopy agrees well with the high-resolution transmission electron microscopy images. Additionally, the polarizations of Raman scattering and the photoluminescence signal from the tip-sample nanogap are explored by combining polarization angle-resolved emission spectroscopy with tip-enhanced optical spectroscopy. Our work demonstrates the significant potential of resolving local structural properties of Si nanomaterials at the sub-10 nanometer scale using tip-enhanced Raman techniques.
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Affiliation(s)
- Marius van den Berg
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
| | - Ardeshir Moeinian
- Institute of Electronic Devices and Circuits, Ulm University, Albert-Einstein-Allee 45, Ulm, Germany
| | - Arne Kobald
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
| | - Yu-Ting Chen
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
| | - Anke Horneber
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
| | - Steffen Strehle
- Institute of Micro- and Nanotechnology, Technische Universität Ilmenau, Max-Planck-Ring 12, Ilmenau, Germany
| | - Alfred J Meixner
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
| | - Dai Zhang
- Institute of Physical and Theoretical Chemistry, Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Eberhard Karls University of Tübingen, Auf der Morgenstelle 15, Tübingen, Germany
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Man Z, Xi Z, Yuan X, Burge RE, Urbach HP. Dual Coaxial Longitudinal Polarization Vortex Structures. PHYSICAL REVIEW LETTERS 2020; 124:103901. [PMID: 32216411 DOI: 10.1103/physrevlett.124.103901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 02/19/2020] [Indexed: 05/07/2023]
Abstract
Carrying orbital angular momentum per photon, the optical vortex has elicited widespread interest. Here, we demonstrate that dual coaxial longitudinal polarization vortices can appear upon a nonparaxial propagation of a tightly focused Pancharatnam-Berry tailored Laguerre-Gaussian beam. Most importantly, it is capable of accessing arbitrary independent topological charges for both vortices, as well as predesigned tunable spacing distances between them.
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Affiliation(s)
- Zhongsheng Man
- School of Physics and Optoelectronic Engineering, Shandong University of Technology, Zibo 255000, China
- Optics Research Group, Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
| | - Zheng Xi
- Optics Research Group, Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
| | - Xiaocong Yuan
- Nanophotonics Research Center, Shenzhen University, Shenzhen 518060, China
| | - R E Burge
- Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
| | - H Paul Urbach
- Optics Research Group, Department of Imaging Physics, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
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