Near-field second-harmonic generation induced by local field enhancement.
The field near a sharp metal tip can be strongly enhanced if irradiated with an optical field polarized along the tip axis. We demonstrate that the enhanced field gives rise to local second-harmonic (SH) generation at the tip surface thereby creating a highly confined photon source. A theoretical model for the excitation and emission of SH radiation at the tip is developed and it is found that this source can be represented by a single on-axis oscillating dipole. The model is experimentally verified by imaging the spatial field distribution of strongly focused laser modes.
Bouhelier
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The Institute of Optics, University of Rochester, Rochester, New York 14627, USA.
Beversluis
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M
Hartschuh
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Novotny
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