Simultaneous independent temperature and strain measurement using in-fibre Bragg grating sensors

A new technique for the simultaneous, independent measurement of temperature and strain using in-fibre Bragg grating sensors is proposed and demonstrated. Two Bragg gratings with closely spaced centre wavelengths are written either side of a splice between two fibres of different diameter. The gratings show similar temperature sensitivities but different strain responses to an applied stress. Maximum errors of +/-17 mu epsilon and +/-1 degrees are reported over 2500 mu epsilon and 120 degrees C measurement ranges.