Investigation of the Extinction Spectra of a Plasmonic Noble-Metal Hollow Nanocube
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Investigation of the Extinction Spectra of a Plasmonic Noble-Metal Hollow Nanocube Min Xiong1 · Cheng Sun1 Received: 7 July 2020 / Accepted: 24 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this work, a hollow cubic nanostructure based on noble metals of silver and gold is studied. The extinction spectra of the plasmonic hollow cube are numerically calculated via the finite-difference time-domain method. A two-peak feature is witnessed in the extinction spectra, and the electric fields at the two resonance wavelengths are computed, indicating two different electromagnetic modes. The resonance wavelengths, the full widths at half maximum, and the peak intensities are also determined from the extinction spectra. In the calculations, the structural parameters of the hollow nanocube are systematically varied, including the cubic size, the thickness of the metallic wall, the geometric ratio of the cube, and the dielectric constants of the inner and outer surrounding media. With changing the structural parameters, the trends revealed in the simulated extinction spectra highlight a great tunability in the plasmonic resonances. Based on the results shown in this work, it is suggested that the proposed metallic hollow nanocube be implemented in designs of plasmonic devices. Keywords Hollow cube · Extinction spectra · Finite-difference time-domain · Plasmonic resonance
Introduction To date, the surface plasmons of nanostructures have been widely investigated both theoretically and experimentally. Thanks to the great properties such as local field enhancements and good tunability, plasmonic nanostructures have been successfully applied in various fields, including surface-enhanced Raman scattering (SERS), optical sensing, optical spectroscopy, subwavelength optics, and surface chemistry [1–6]. When the frequency of the incident light matches that of the surface plasmons, their energies and momenta are effectively coupled, and plasmonic resonance occurs. Based on the plasmonic resonance, a variety of promising applications in optical sensing, optical switching and modulation, and nonlinear optical devices have been studied [7–11]. Among various plasmonic nanostructures, the coreshell scheme has been shown to be attractive, since it exhibits a substantial field enhancement and a wide range tunability in plasmonic resonances [12–16]. For example, Cheng Sun
[email protected] 1
College of Physical Science and Technology, Dalian University, Dalian, 116622, China
three plasmonic resonance peaks were calculated in the absorption spectrum of a bimetallic multilayer core-shell structure, which were suitable for SERS-based multiplex biosensing [17]. Localized surface plasmon resonances (SPR) of a Ag-dielectric-Ag multilayered nanoshell were theoretically studied, and the absorption spectrum was shown to be influenced by the refractive index of the surrounding medium, as well as the layers’ thicknesses [18]. In addition, based on the investigation of the extinction spectra of the sp
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