Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 5: Plasmonics: Nanoantennas, Nanoparticles
O 5.5: Vortrag
Montag, 16. März 2015, 11:30–11:45, MA 042
Fano resonances and near-field coupling efficiency in plasmonic nanostructures based on nanorods — •Manuel Gonçalves1, Madeleine Nilsen1, Ines Martin1, Taron Makaryan2, Armen Melikyan3, Hayk Minassian4, and Othmar Marti1 — 1Ulm University - Inst. of Experimental Physics, Ulm, Germany — 2Yerevan State University - Radiophysics Department, Yerevan Armenia — 3Russian-Armenian (Slavonic) University, Yerevan, Armenia — 4Yerevan Physics Institute, Yerevan, Armenia
Nanorods present well separated dipolar and higher order multipolar plasmon resonances. These resonances scale up approximately with the aspect ratio. Several configurations of rods of non-identical size can be used to produce Fano resonances, by coupling one radiant mode (dipole) with one sub-radiant mode (quadrupole). The near-field coupling between rods arranged in T- and H-like configurations is very efficient and leads to well pronounced Fano resonances in the absorption and scattering spectra. On the other hand, these structures are among the most simple to fabricate.
We have investigated several structures by varying the geometrical and optical parameters and their influence in the Fano resonance. The near-field coupling between rods can be quantitatively characterized, using the ratio between absorption cross sections calculated separately for each part of the resonant system. At the Fano resonance this ratio achieves a maximum. It can also be generalized for other structures presenting Fano resonances, like heptamers and pentamers of coupled disks.