<title>Evanescent field refractive index sensor utilizing a narrow fiber Bragg grating and a tunable DBR laser</title>

Abstract

We have demonstrated an evanescent field refractive index fiber sensor comprising a 42 mm Bragg grating in an etched fiber together with a tunable DBR laser. Characterization of different aqueous sucrose solutions resulted in a resolution of roughly 10 mM sucrose. The sensor in the presented form has a theoretical sensitivity of higher than 10<SUP>-5</SUP> refractive index units (riu) in a refractive index region close to the cladding index of the fiber. However, the technique allows for an even higher sensitivity than 10<SUP>-6</SUP> riu with a proper signal processing scheme.