Preparation optimization for a silver cavity coupled tapered fiber SERS probe with high sensitivity

Abstract

A cavity coupled optical fiber decorated by Ag nanoparticles (AgNPs) as the surface-enhanced Raman scattering (SERS) substrate is discussed, and the localized surface plasmon resonance (LSPR) of AgNPs and a cavity enhancement of a silver capillary simultaneously contribute to Raman enhancement. AgNPs were coated on the tapered fiber surface using multiple cycle light induced deposition technology. During the process, two key parameters including the evaporation time and the deposition recycling times were optimized to find an effective coverage of AgNPs. In addition, the forming mechanism based on different distributions of the temperature field and velocity field was discussed. The effect of the cavity length was analyzed. Experiments with R6G (rhodamine 6G) as analyte show that the limit of detection can be down to 10−11 mol/L, with a total enhancement factor (EF) of ∼109, while an additional cavity coupled EF could be ∼7.