Thinned and micro-structured fibre Bragg gratings: towards new all-fibre high-sensitivity chemical sensors

In this work, recent developments of a new class of all-fibre and high-sensitivity refractive index sensors based on thinned and micro-structured fibre Bragg gratings (FBGs) are reported. Uniform and non-uniform thinned FBGs (ThFBGs) have been proposed for refractive index measurements providing self temperature referencing with performances adequate to the state of the art. Furthermore, micro-structured FBGs have been developed as advanced refractive index sensors able to provide low-cost and high-sensitivity refractive index sensors for chemical sensing. Here, analysis, fabrication and characterization of the proposed optoelectronic devices are presented. Finally preliminary studies on two-defect micro-structured gratings are presented.