Sensing with photonic crystal fibres

Fast, frequent, accurate and reliable measurements of physical quantities such as temperature, stress or strain are known to be of utmost importance in areas such as process industry or structural health monitoring. Photonic crystal fibres (PCF) (Bjarklev et al., 2003) constitute a class of optical fibres that has a large potential for a number of novel applications in the sensing domain. The manufacturing flexibility of PCF allows fabricating different types of specialty microstructured fibres including endlessly single mode, double clad, germanium or rare earth doped, highly birefringent, and many other fibres with particular features. In this paper we analyse several of these and describe how they can be exploited for sensing applications. We pay particular attention to temperature and hydrostatic pressure sensitivities. We also report on new microstructure geometries dedicated to sensing applications and on Bragg gratings written in highly birefringent photonic crystal fibre.