Influence of symmetry breaking in pentamers on Fano resonance and near-field energy localization

Abstract

Arrays of asymmetric pentamers are designed and fabricated with an offset of the central nano-disk position to study the effect of symmetry breaking in pentamers. It is found that while planar symmetric oligomers can exhibit a single Fano Resonance (FR), an offset of the central nano-disk at a controlled gap of 3 nm from the nearest neighbor nano-disk, gives rise to the appearance of an additional dark mode that can potentially be used in localized surface plasmon resonance sensing. It is shown that this mode leads to the appearance of the second FR in the same spectrum. The simulation results are in a good agreement with experimental data. Furthermore, it is found that unique near-field energy distribution in the asymmetric pentamers can be well tuned to be localized at one, two or three of the four subwavelength gaps of the pentamer selectively by only changing the polarization orientation of a single light source.

Double Fano resonances in nanoring cavity dimers: The effect of plasmon hybridization between dark subradiant modes

“…43,44 It is shown that Fano-like resonances can be generated by deconstructing plasmonic nanoclusters, 45,46 and multiple Fano resonances can be obtained via this approach. 47 It also demonstrates that because of the excitation of higher order dark modes, multiple Fano resonances are generated in enlarged oligomer clusters. 20 However, there is a large energy gap between the multiple Fano resonances, which is unfavorable for SERS application.…”

Investigation of Fano Resonances Induced by Higher Order Plasmon Modes on a Circular Nano-Disk With an Elongated Cavity

“…In this work, the RLC circuit shown in Fig. 7(a) is used for this purpose; the mathematical model of this RLC circuit is similar to that of the mass-spring oscillator developed in [53] to model two distinct Fano resonances. The spectrum of the power drawn by the RLC circuit can be used to mathematically imitate the extinction CS spectrum of the designs with two plasmon modes D 2 and Q 1 (Section 2.2) and three plasmon modes D 3 , D 4 , and Q 2 (Section 2.3).…”

“…It is well known that any physical Fano resonance can be mathematically modeled using a multi-resonance coupled system of oscillator equations [35]. To this end, the mass spring model has been accurately applied in explanation of one or two Fano resonances observed in the extinction cross-section (CS) spectrum of various nano-scale devices [35,[42][43][44]53].…”

Multiple Fano resonances in bimetallic layered nanostructures

“…The plasmonic Fano-like resonances exhibit sharp resonance and strong light confinement and are analogues of electromagnetically induced transparency (EIT) [1]. They have been observed in various symmetric and asymmetric metallic nanostructures that include nanoshells [2][3][4][5][6], multilayered nanocones [7], rings [8][9][10][11][12], dimers [13][14][15][16][17][18][19][20], trimers [21,22], quadrumer [23,24], pentamers [25,26], hexamer [27], and nanoparticle chains [28,29]. Among all the nanostructures, the plasmonic layered nanostructures have attracted many researchers attention because these structures exhibiting multiple Fano resonances over the entire visible spectrum as well as near to mid infrared region.…”