Fabrication and evaluation of a localized plasmon resonance probe for near-field optical microscopy/spectroscopy

A technique that excites a localized plasmon on the apex of probe for near-field optical microscope and spectroscope is presented. Vapor deposition and heating of several tens nm thick gold films on 1 nm thick germanium-covered tapered optical fiber probe make highly adherent and smooth overlayers. A "tunneling-photon-mode" experimental system combined with a dye laser is used to excite a localized plasmon. The enhancement of near-field intensity was measured varying incident photon energies with its maximum occurring at 2.11 eV. This local field enhancement could be estimated to generate only in the close proximity of the substrate. (C) 1998 American Institute of Physics.