Highly-efficient fluorescence sensing using microstructured optical fibres; side-access and thin-layer configurations

Abstract

A model is presented for calculating the performance of fluorescence-based optical-fibre sensors that considers the full vectorial nature of optical-fibre electromagnetic-field solutions making it suitable for modeling microstructured optical fibres with wavelength and sub-wavelength-scale features. By applying the model to a specific fibre geometry it is shown that high-index, small core (subwavelength) fibres allow for enhanced fluorescence capturing due to the formation of a thin, high-intensity layer at the core-cladding boundary. The model is evaluated in this regime for two sensing configurations of particular interest for future sensing systems, a side-access sensor for liquid-based sensing and a thin-layer (surface) sensor. Both configurations can offer improvements for fluorescence-based sensing.