INTRINSIC FIBER FABRY-PEROT SENSORS BASED ON CO-LOCATED BRAGG GRATINGS

An improved low-coherence optical fibre Fabry-Perot sensor, based on m ultiple co-located pairs of fibre Bragg gratings, is presented. Throug h the use of two (or more) reflection wavelengths and a compatible bro adband source or sources, a sensor output of the form obtained in mult iple-wavelength low-coherence interferometry is achieved. This allows easier identification of the centre of the fringe pattern than is poss ible with just a single pair of Bragg gratings. Modelling of the senso r behaviour with two or three pairs of gratings is discussed, and temp erature measurement results with a triple Fabry-Perot are presented. ( C) 1997 Elsevier Science B.V.