Photonic technologies have played a key role in the last decades to address the high demand for data traffic by telecommunication networks and data centres. The industrial development of Wavelength Division Multiplexing (WDM) optical communications systems and networks in the nineties and the more recent interest in photonic integration for data centres to overcome their well-known electronic bottleneck, have driven the technology to a high level of maturity, opening the way to many other industrial fields and applications. In particular, photonic technologies are becoming extremely attractive for sensing applications in a wide range of industrial fields, including energy, oil & gas, transportation, automotive, aerospace, bio-chemical and medical applications, as well as for structural health and environmental monitoring. Optical fibre sensors and photonic sensors, in general, offer many advantages compared to conventional electronic-based sensors; immunity to electromagnetic interference, small size and weight, high multiplexing capabilities, robustness to harsh environments, as well as the fact of being completely passive at the sensing points.