Nanostructured optical fibre for surface-enhanced Raman scattering sensing

Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic tool for detecting low concentrations of many substances. The SERS effect occurs when a Raman active molecule is in contact with a metal surface having nanoscale features. While common SERS surfaces are formed on planar substrates, we present a technique whereby the surface is fabricated on the tips of custom designed optical fibres. The fibre presented is based on a modified imaging fibre which consists of a bundle of thousands of micron-sized individual optical fibres fused together in a coherent bundle. The fibre is then drawn such that each pixel is reduced to a nanoscale size. When chemically etched, the cores of the drawn pixels are eroded leaving an array of nanostructured wells. These are then coated with a thin layer of silver to enable SERS functionality. The design of the fibre, the manufacturing and etching processes and the characterisation of the SERS functionality will be presented.