ABSTRACT
Fibre Bragg gratings (FBGs) have been the subject of intense research since the early 1990s (though their birth actually lies in the late 1970s). Whilst it is fair to say that most of the drive for this research has been related to applications in optical communications, nevertheless a considerable effort has been devoted towards developing gratings suitable for sensing and applying them in many diverse fields. The main attraction from the sensing point of view is that, as we shall shortly see, the sensor is, in effect, formed inside the optical fibre itself, rather than by the addition to the fibre of any external components. This leads to a device that is very compact and thus well suited to incorporation within structures where space is at a premium. Moreover, gratings lend themselves very nicely to applications requiring the multiplexing of many sensors.
