Surface-enhanced Raman Scattering sensor based on fused biconical taper fiber

In this paper a novel Surface-enhanced Raman Scattering (SERS) sensor combining with fused taper optical fiber (FBTF) and the film coating with silver sols is proposed. This structure is designed to obviously increase the SERS active surface when the radius is reduced and the length of the taper is increased, because the penetration depth is proportional to the taper length and inversely proportional to the taper radius according to the fiber-optic evanescent-wave theory. Based on the SERS sensing principle, the feasibility of FBTF sensor is analyzed in this paper. Actually, the Raman spectrum of R6G is obtained from the taper surface coating with the silver sols in our experiments. The detecting concentration is up to 10–7M. Moreover, this SERS sensing structure is simple and reproducible.