ORCID Profile
0000-0003-2925-682X
Current Organisation
Nanyang Technological University
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Publisher: American Chemical Society (ACS)
Date: 03-05-2016
Publisher: American Chemical Society (ACS)
Date: 25-06-2012
DOI: 10.1021/NN3022684
Abstract: The sharpness of corners/edges can have a large effect on the optical responses of metallic nanostructures. Here we deploy the theory of transformation optics to analytically investigate a variety of blunt plasmonic structures, including overlapping nanowire dimers and crescent-shaped nanocylinders. These systems are shown to support several discrete optical modes, whose energy and line width can be controlled by tuning the nanoparticle geometry. In particular, the necessary conditions are highlighted respectively for the broadband light absorption effect and the invisibility dips that appear in the radiative spectrum. More detailed discussions are provided especially with respect to the structures with asymmetric edge rounding. These structures can support additional subradiant modes, whose interference with the neighboring dipolar modes results in a rapid change of the scattering cross-section, similar to the phenomenon observed in plasmonic Fano resonances. Finite element numerical calculations are also performed to validate the analytical predictions. The physical insights into blunt nanostructures presented in this work may be of great interest for the design of broadband light-harvesting devices, invisible and noninvasive biosensors, and slowing-light devices.
Publisher: American Chemical Society (ACS)
Date: 03-10-2016
Publisher: American Chemical Society (ACS)
Date: 19-06-2019
Abstract: When the geometric features of plasmonic nanostructures approach the subnanometric regime, nonlocal screening and charge spill-out of metallic electrons will strongly modify the optical responses of the structures. While quantum tunneling resulting from charge spill-out has been widely discussed in the literature, the near-field enhancement saturation caused by the nonlocal screening effect still lacks a direct experimental verification. In this work, we use surface-enhanced Raman spectroscopy (SERS) of graphene to probe the in-plane near-field enhancement limit in gold nanosphere-on-film nanocavities where different layers of graphene are sandwiched between a gold nanosphere and a gold film. Together with advanced transmission electron microscopy cross-sectional imaging and nonlocal hydrodynamic theoretical calculations, the cavity gap width correlated SERS and dark-field scattering measurements reveal that the intrinsic nonlocal dielectric response of gold limits the near-field enhancement factors and mitigates the plasmon resonance red-shift with decreasing the gap width to less than one nanometer. Our results not only verify previous theoretical predictions in both the near-field and far-field regime but also demonstrate the feasibility of controlling the near- and far-field optical response in such versatile plasmonic particle-graphene-on-film nanocavities, which can find great potential in applications of graphene-based photonic devices in the visible and near-infrared region.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2020
Publisher: American Chemical Society (ACS)
Date: 20-09-2008
DOI: 10.1021/NL303377G
Abstract: The optical properties of three-dimensional crescent-shaped gold nanoparticles are studied using a transformation optics methodology. The polarization insensitive, highly efficient, and tunable light harvesting ability of singular nanocrescents is demonstrated. We extend our approach to more realistic blunt nanostructures, showing the robustness of their plasmonic performance against geometric imperfections. Finally, we provide analytical and numerical insights into the sensitivity of the device to radiative losses and nonlocal effects. Our theoretical findings reveal an underlying relation between structural bluntness and spatial dispersion in this particular nanoparticle configuration.
Publisher: Springer Science and Business Media LLC
Date: 15-04-2015
DOI: 10.1038/SREP09590
Abstract: We theoretically demonstrated and experimentally verified high-order radial spoof localized surface plasmon resonances supported by textured metal particles. Through an effective medium theory and exact numerical simulations, we show the emergence of these geometrically-originated electromagnetic modes at microwave frequencies. The occurrence of high-order radial spoof plasmon resonances is experimentally verified in ultrathin disks. Their spectral and near-field properties are characterized experimentally, showing an excellent agreement with theoretical predictions. Our findings shed light into the nature of spoof localized surface plasmons and open the way to the design of broadband plasmonic devices able to operate at very different frequency regimes.
Publisher: American Chemical Society (ACS)
Date: 29-12-2010
DOI: 10.1021/NN102819P
Abstract: The plasmonic interaction between overlapping nanowires with and without structure singularities is studied analytically and numerically. A conformal transformation approach is adopted to predict analytically the optical response of overlapping nanowires in the quasi-static limit. Surface plasmon excitations are shown to exhibit a lower bound cutoff frequency, which blue-shifts when the overlap distance increases. Between this cutoff and the surface plasmon frequencies, overlapping nanowires are capable of a strong and broad-band harvesting of light. This band gap feature is shown to be robust to radiative losses and to the bluntness of the structure singularities. Hence, the light harvesting performance of overlapping nanowires would not be damaged by nanofabrication imperfections. These remarkable features might be beneficial to the realization of plasmonic band gap filters.
Publisher: Springer Science and Business Media LLC
Date: 12-2013
Publisher: American Physical Society (APS)
Date: 20-06-2014
Publisher: American Physical Society (APS)
Date: 11-01-2012
Publisher: Wiley
Date: 08-08-2019
Publisher: American Physical Society (APS)
Date: 28-12-2012
Publisher: American Chemical Society (ACS)
Date: 08-12-2017
Publisher: American Physical Society (APS)
Date: 02-12-2015
Publisher: American Physical Society (APS)
Date: 08-09-2015
Publisher: American Physical Society (APS)
Date: 24-01-2019
Publisher: American Physical Society (APS)
Date: 26-08-2013
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Yu Luo.