Interference, coupling, and nonlinear control of high-order modes in single asymmetric nanoantennas.
We investigate theoretically and experimentally the structure of plasmonic modes in individual asymmetric dimer antennas. Plasmonic near-field coupling of high-order modes results in hybridization of bright and dark modes of the individual nanorods, leading to an anticrossing of the coupled resonances. For two bright modes, hybridization results in a capacitive red shift and super-radiant broadening. We show that the properties of asymmetric dimers can be used for nonlinear control of spectral modes and demonstrate such a nonlinear effect by measuring the modulation of a hybrid asymmetric dimer--ITO antenna. With use of full electrodynamical calculations, we find that the properties of the near-field nonlinear responses are distinctly different from the far-field, which opens up new routes for nonlinear control of plasmonic nanosystems.
SEPnet and Physics and Astronomy, Faculty of Physical and Applied Sciences, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
Martina
M
Abb
Yudong
Y
Wang
Pablo
P
Albella
C H
CH
de Groot
Javier
J
Aizpurua
Otto L
OL
Muskens