Sensitivity improvements of exposed-core microstructured optical fibre Bragg grating refractive index sensors

Abstract

G. Tsiminis andFemtosecond laser written Bragg gratings have been written in various exposed-core microstructured optical fibres (ECMOFs) for the first time. The EC-MOFs have different core diameters ranging from 2.7 micrometers to 12.5 micrometers and offer different degrees of core access depending on application requirements. Writing a Bragg grating on an open core fibre allows for refractive index based sensing, with a view to multiplexed biosensing. Smaller core fibres are shown both experimentally and theoretically to provide a higher sensitivity, with experimental sensitivities demonstrated up to 6.4 nm/RIU over the refractive index range from 1.333 (water) to 1.377 (isopropanolexperiments).