Compact refractive index sensor based on an S-tapered fiber probe

Abstract

We have demonstrated a refractive index (RI) sensor based on an S-tapered fiber probe (STFP) with a silver mirror on its end facet. The fiber probe has a compact size of about 1 mm, making it proper for sensing in narrow or limited space. The reflection spectra of the STFPs with different structure lengths have been analyzed and simulated. Its RI sensitivity in the range of 1.332 ~1.387 reaches 268.8 nm/RI unit, which is 9 times higher than that of the existing reflective fiber-taper-based RI sensor. Furthermore, the thermal response experimental results show that the STFP is temperature insensitive.