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.
Optical fiber surface-enhanced Raman scattering (SERS) sensors offer a potential solution to monitoring low chemical
concentrations in-situ or in remote sensing scenarios. We demonstrate the use of nanoimprint lithography to fabricate
SERS-compatible nanoarrays on the end faces of standard silica optical fibers. The antireflective nanostructure found on
cicada wings was used as a convenient template for the nanoarray, as high sensitivity SERS substrates have previously
been demonstrated on these surfaces. Coating the high fidelity replicas with silver creates a dense array of regular
nanoscale plasmonic resonators. A monolayer of thiophenol was used as a low concentration analyte, from which strong
Raman spectra were collected using both direct endface illumination and through-fiber interrogation. This unique
combination of nanoscale replication with optical fibers demonstrates a high-resolution, low-cost approach to fabricating
high-performance optical fiber chemical sensors.