Investigation of the fano lineshapes in plasmonic asymmetric silver nanosphere dimer

Abstract

The plasmonic properties of an asymmetric dimer, comprising of two silver nanospheres with different radii, are studied by the finite difference time domain method. The extinction efficiencies of the plasmonic dimer are numerically calculated in the visible and near-infrared regime, i.e., from 950THz to 150THz. Two distinguishable Fano resonances are observed when the separation between the nanospheres is narrowed within a certain value, e.g., less than 10nm. The extinction spectrum that presents two Fano resonances, associated with two electromagnetic modes, is well fitted using a model consisting of two Fano lineshape functions. The resonance frequencies, the spectral widths, and the characteristic q values are obtained via the best fit parameters, and their trends are revealed with varying the radii of the nanospheres. The fitting scheme proposed in this work may be useful in the study of other plasmonic nanostructures with multiple Fano resonances.

Plasmonic characteristics of rhodium dual broken nanorings in UV–visible regime

“…2a, the double-peak feature in the scattering efficiency curve is a manifestation of two Fano resonances, and hence the scattering efficiency (indicated in 'S') may be fitted to Eq.2, which consists of two Fano lineshape functions. Note that similar treatments were successfully implemented in previous work [26].…”

On the Plasmonic Properties of a Bi-Metallic Eccentric Ring-Disk Nanostructure

“…Similarly, in plasmonic nanostructures, Fano resonance may also be induced by a strong coupling effect between the discrete and the continuous plasmonic modes, resulting in an asymmetric lineshape in the spectrum [17,18,19,20]. For example, the plasmonic properties of an asymmetric dimer that was consisted of two silver nanospheres were probed, and two distinguishable Fano resonances were revealed in the extinction spectrum, and well fitted to a model consisting of two Fano functions [21]. In addition, the plasmonic effects of a symmetry-breaking system constituted with two rhodium broken nanorings were studied in the ultraviolet-visible regime, and multiple Fano resonances were also observed in the scattering spectrum and were quantitatively addressed [22].…”

On the plasmonic properties of a bi-metallic eccentric ring-disk nanostructure

“…Similarly, in plasmonic nanostructures, Fano resonance may also be induced by a strong coupling effect between the discrete and the continuous plasmonic modes, resulting in an asymmetric lineshape in the spectrum [17,18,19,20]. For example, the plasmonic properties of an asymmetric dimer that was consisted of two silver nanospheres were probed, and two distinguishable Fano resonances were revealed in the extinction spectrum, and well fitted to a model consisting of two Fano functions [21]. In addition, the plasmonic effects of a symmetry-breaking system constituted with two rhodium broken nanorings were studied in the ultraviolet-visible regime, and multiple Fano resonances were also observed in the scattering spectrum and were quantitatively addressed [22].…”