We study optical second harmonic generation from metallic dipole antennas with narrow gaps. Enhancement of the fundamental- frequency field in the gap region plays a marginal role on conversion efficiency. In the symmetric configuration, i.e., with the gap located at the center of the antenna axis, reducing gap size induces a significant red-shift of the maximum conversion efficiency peak. Either enhancement or inhibition of second-harmonic emission may be observed as gap size is decreased, depending on the antenna mode excited at the harmonic frequency. The second-harmonic signal is extremely sensitive to the asymmetry introduced by gap’s displacements with respect to the antenna center. In this situation, second-harmonic light can couple to all the available antenna modes. We perform a multipolar analysis that allows engineering the far-field SH emission and find that the interaction with quasi-odd-symmetry modes generates radiation patterns with a strong dipolar component.

Role of antenna modes and field enhancement in second harmonic generation from dipole nanoantennas

VINCENTI, MARIA ANTONIETTA;DE ANGELIS, Costantino;LOCATELLI, Andrea;DE CEGLIA, DOMENICO
2015-01-01

Abstract

We study optical second harmonic generation from metallic dipole antennas with narrow gaps. Enhancement of the fundamental- frequency field in the gap region plays a marginal role on conversion efficiency. In the symmetric configuration, i.e., with the gap located at the center of the antenna axis, reducing gap size induces a significant red-shift of the maximum conversion efficiency peak. Either enhancement or inhibition of second-harmonic emission may be observed as gap size is decreased, depending on the antenna mode excited at the harmonic frequency. The second-harmonic signal is extremely sensitive to the asymmetry introduced by gap’s displacements with respect to the antenna center. In this situation, second-harmonic light can couple to all the available antenna modes. We perform a multipolar analysis that allows engineering the far-field SH emission and find that the interaction with quasi-odd-symmetry modes generates radiation patterns with a strong dipolar component.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11379/457951
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