FIBER OPTICAL BRAGG GRATING REFRACTOMETER

We have demonstrated an evanescent field refractive index fiber sensor comprising a 42-mm Bragg grating in an etched fiber together with a t unable Distributed Bragg Reflector (DBR) laser. Characterization of di fferent aqueous sucrose solutions resulted in a resolution of roughly 10 mM sucrose. The sensor in the presented form has a theoretical sens itivity of higher than 10(-5) refractive index unit (riu) in a refract ive index region close to the cladding index of the fiber. However the technique allows for an even higher sensitivity than 10(-6) riu with a proper signal processing scheme.