Spectral width reduction in lossy mode resonance-based sensors by means of tapered optical fibre structures

This contribution pursues the goal of achieving an optical fibre-based platform to detect anti-gliadin antibodies (AGAs), in order to early diagnose celiac disease. To this purpose, the generation of lossy mode resonances (LMRs) in several evanescent field optical structures was studied both theoretically and experimentally. LMRs were obtained by adsorbing a polymeric thin-film onto the optical structures using the layer-by-layer assembly technique. The LMR shape depends on the geometry of the optical structure and its attenuation was controlled just by tuning the length of the device. The best performance was obtained with tapered single-mode optical fibres, which provided more than a 50% reduction in the spectral width of the LMR by using a shorter device. This improvement was successfully applied to detect anti-gliadin antibodies (AGAs) in 5 ppm concentration, what can be used to diagnose celiac disease, and shows the potential of this technology to address biosensing applications.