Polarization-controlled spatial localization of near-field energy in planar symmetric coupled oligomers |
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Authors: | M?Rahmani B?Lukiyanchuk T?Tahmasebi Y?Lin T?Y?F?Liew Email author" target="_blank">M?H?HongEmail author |
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Institution: | (1) Data Storage Institute, (A*STAR) Agency for Science, Technology and Research, 5 Engineering Drive 1, Singapore, 117608, Singapore;(2) Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117576, Singapore; |
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Abstract: | Arrays of planar symmetric coupled oligomers support higher sensitivity optical response than uncoupled plasmonic systems.
In this work, the transition from isolated to collective optical modes in plasmonic oligomers, such as pentamers and quadrumers,
is investigated via experimental characterization and simulation with good agreement. The designed and fabricated metallic
oligomers consist of a single central disk and outer ring-like disks in nanoscales. It is shown that while the far-field spectral
responses of oligomers are polarization-independent, due to the structure symmetry, the spatial localization of near-field
energy in nanogaps can be polarization-controlled. This localization is established at a normal-incident light of a single
source rather than co-illumination by two light sources accompanied by different incident angles or phase shift. It can overcome
the spatial restrictions of conventional optics. The influence of the nano-disk sizes and gaps among them on the intensity
and shape of the localized near-field energy in pentamers and quadrumers is also studied. |
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