Abstract
The optical properties of a dimer type nanoantenna loaded with a plasmonic nanoring are investigated through numerical simulations and measurements of fabricated prototypes. It is demonstrated that by judiciously choosing the nanoring geometry it is possible to engineer its electromagnetic properties and thus devise an effective wavelength dependent nanoswitch. The latter provides a mechanism for controlling the coupling between the dimer particles, and in particular to establish a pair of coupled/de-coupled states for the total structure, that effectively results in its dual mode response. Using electron beam lithography the targeted structure has been accurately fabricated and the desired dual mode response of the nanoantenna was experimentally verified. The response of the fabricated structure is further analyzed numerically. This permits the visualization of the electromagnetic fields and polarization surface charge distributions when the structure is at resonance. In this way the switching properties of the plasmonic nanoring are revealed. The documented analysis illustrates the inherent tuning capabilities that plasmonic nanorings offer, and furthermore paves the way towards a practical implementation of tunable optical nanoantennas. Additionally, our analysis through an effective medium approach introduces the nanoring as a compact and efficient solution for realizing nanoscale circuits.
Highlights
Is devised by removing small bits of material from around the center of a nanobar
In this paper through experiments and numerical simulations we investigate the feasibility of tuning the optical response of a nanodimer using plasmonic nanorings
In the current manuscript a planar version of that nanoantenna configuration is studied where the cylindrical nanodipole is substituted by a circular disk dimer, while the core-shell load is represented by a nanoring
Summary
Is devised by removing small bits of material from around the center of a nanobar In both cases, the structure modification creates an effect equivalent to that of an electrically small circuit that loads and tunes the impedance response of a nanoantenna. In this paper through experiments and numerical simulations we investigate the feasibility of tuning the optical response of a nanodimer using plasmonic nanorings It has been well-documented that the resonance properties of plasmonic nanodimers are primarily determined by the gap distance between their two constituent particles [17,18,19]. It should be noted here that this manuscript can be considered as a companion to our previously published work in [25] In that paper it was theoretically demonstrated how the response of a nanodipole can be custom engineered using plasmonic core-shell particles. The radiation properties of these modes correspond to the states where the two particles of the dimer radiate either independently or collectively
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