Metallic-Dielectric colloidal photonic crystal on the multimode optical fiber tip: preliminary results as optical fiber SERS probe

We present an optical fiber device involving metal-dielectric colloidal crystal (MDCC) structures as a platform for surface enhanced Raman-scattering (SERS) sensing applications. The MDCC structures received large interest in last years since they permit to combine localized surface plasmonic resonance (LSPR) of noble metallic nanoparticles and photonic bandgap (PBG) of colloidal type photonic crystals (PhCs). Most of the MDCC structures have been provided onto planar substrates and then investigated as SERS platform. However, the integration and/or combination of the advantages MDCC structures with optical fiber technology represent still open challenges. The present paper reports recent results about MDCCs fabricated directly onto fiber optic tip surface by successive depositions of Au-NPs on PS-based CCs. Our goal is the fabrication of miniaturized fiber optic devices for SERS sensing applications. Numerical and experimental results of different samples are here presented and discussed. For the sensing test, the fiber probes were immersed in a 100 mu M ethanol solution of 4-Mercaptobenzoic acid (4MBA). Then, preliminary SERS results were retrieved by a Labspec Aramis confocal Raman spectrometer.