Characterization of an encapsulated long period grating transducer applied as a refractometer

This work presents the applicability of an encapsulated long period grating for fuel blends and solvents analysis. It was shown that the optical fiber device sensitivity to changes in the external refractive index is not affected by the encapsulation. In addition to the extra protection to external damages provided by the encapsulation, the device reproducibility was considerably improved. For the employed samples this improvement ranges from 40% to 78%. Finally the transducer performance was assessed in the analysis of ethanol concentration in ethanol-water mixture.