Multiple Fano resonances in bimetallic layered nanostructures

Abstract

Plasmonic Fano resonances arise in bimetallic layered nanostructures (metal-dielectric-metal and dielectric-metal-dielectric-metal) are studied theoretically as the function of their geometrical parameters. Multiple Fano resonances are generated in these nanostructures where several subradiant dark modes appear due to the geometrical symmetry breaking induced by offsetting different layers. The plasmonic responses of the proposed nanoparticles with equal volumes are compared and multiple Fano resonances with large modulation depths are obtained in metal-dielectric-metal structure which is highly suitable for multi-wavelength sensing and plasmon line shaping. However, the dielectric-metal-dielectricmetal nanostructure is found to provide a slightly better tunability of higher-order plasmonic modes compared to metal-dielectric-metal nanostructure due to which it can be useful for biomedical applications.

Twin Dipole Fano Resonances in Symmetric Three-Layered Plasmonic Nanocylinder

“…Other plasmonic bimetallic layered nanostructures like ring/disk nanocavities (RDNC) [14,31,36] and double nanoshell structure (DNS) [9] exhibit the similar superradiant mode, subradiant mode, and single dipole Fano resonance in the concentric case. For the achievement of multiple Fano resonances in RDNC and DNS nanostructures, the same symmetry breaking conception is used [10,14,37]. The symmetry reduced metal nanostructures are usually fabricated using complex and expensive techniques, which severely reduces their application potentials.…”

“…Recently, these resonances are studied in all types of plasmonic nanosystems due to the potential applications in metamaterials, surface-enhanced Raman spectroscopy (SERS), sensing, and slow-light devices [2][3][4][5][6][7]. These nanostructures include nanoshells [8][9][10][11], nanocones [12,13], ring/disk nanocavities [14][15][16], dimers [17][18][19], trimers [20], and nanoparticle aggregates [21,22], where the Fano resonance arises from the destructive interference of symmetric bright mode with the asymmetric dark plasmon mode.…”

“…The concept of symmetry breaking has also been introduced in several plasmonic nanostructures like the multilayered nanoshells [10,23], nanocross [24], dual-disk ring [14], and nanodisk with a missing wedge [25] for the generations of higher-order multiple Fano resonances. In all these structures, multiple higher-order dark modes appear in the optical spectrum, which couples to the bright dipolar mode and induces higher-order multiple Fano resonances.…”

Tunable Fano Resonances and Electromagnetically Induced Transparency in All-Dielectric Holey Block

“…In plasmonic nanosystems, EIT and Fano resonances usually originate from the destructive interference of a narrow band and broad band spectra, which results in a sharp asymmetric line shape [9][10][11][12][13][14][15][16][17][18]. The line shape of such resonances is highly sensitive to the local dielectric medium and geometry of the nanoparticle.…”

Multiple higher-order Fano resonances in plasmonic hollow cylindrical nanodimer

“…He observed that destructive and constructive interferences take place due to the overlapping of a discrete state with a continuum state, which results in the asymmetric profile. Over the past few years, plasmonic nanosystems have been investigated for the generation of Fano resonances with sharp dispersion [2][3][4][5][6][7][8][9][10][11][12]. In such systems, Fano resonance arises due to the spectral overlapping of broad superradiant and narrow subradiant plasmon modes, which are usually characteristics of dipolar and higher-order plasmon modes, respectively.…”