A gold nanotip enhanced optical fibre device for plasmonic near-field microscopy

Localized surface plasmon resonances (LSPRs) are collective oscillations of the electron ensemble in a metallic nanostructure and can be excited by electromagnetic (EM) waves. Their characteristics are determined by the morphology of the nanostructure and the permittivities of the metal and the surrounding dielectric. An intriguing feature of LSPRs is the local EM field enhancement, resulting in strong EM energy localization at sharp corners or edges [1]. Metal nanotips in particular are of considerable interest in tip-enhanced Raman spectroscopy (TERS), biophotonic sensing and single-molecule experiments.In this paper we present a novel technique for collecting the scattered light from a LSPR at a metallic nanotip. By splicing a cone-shaped gold nanowire to the end of a multimode fibre (MMF), light from the LSPR is collected using the fibre.