Practical sensitive fluorescence sensing with microstructured fibres

Abstract

We demonstrate a new detection limit for fluorescent species in small-core glass microstructured optical fibres. Two detection schemes are explored: forward detection by an optical spectrum analyser; and backward detection by a photodiode. In the second scheme, characterisation of the fluorescence signal during fibre filling allows us to accurately separate quantum-dot fluorescence from intrinsic glass fluorescence. The spectral overlap of these two fluorescence sources is the principal limit to the detection sensitivity. We demonstrate a detection limit of ∼200 pM. © 2009 SPIE.