title: Near-field second-harmonic generation induced by local field enhancement.
abstract: 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.
authors.affiliation: The Institute of Optics, University of Rochester, Rochester, New York 14627, USA.
authors.forename: A
authors.initials: A
authors.lastname: Bouhelier
authors.forename: M
authors.initials: M
authors.lastname: Beversluis
authors.forename: A
authors.initials: A
authors.lastname: Hartschuh
authors.forename: L
authors.initials: L
authors.lastname: Novotny