Tailoring the temperature responsivity of fibre Bragg gratings [temperature/strain sensors]

We propose and demonstrate different techniques to fabricate fibre Bragg gratings (FBGs) of various temperature responsivity. Temperature responsivity values ranging from 7.49 pm/°C to 12.24 pm/°C have been successfully achieved for the sensors written in B/Ge fibres with different UV exposure time, which allows for co-measurement of temperature and axial strain of magnitude up to 7200 με. The dual-parameter sensing functionality of the sensors originates from their unique configuration of having two Bragg reflection peaks that exhibit the same strain- but different temperature responses. The wide range of responsivity values indicates that the responsivity of the grating peaks can be tailored. The advantages of tolerance of very large strain effects and more importantly, the use of a single light source for interrogation, offer the prospects of a practical temperature independent strain measurement system.