Strain-temperature discrimination using a step spectrum profile fibre Bragg grating arrangement

A sensing head for simultaneous measurement of temperature and strain is presented and analyzed. The proposed configuration is based on the combination of two Bragg gratings, written in different fibres and with different reflectivities, to form a single signature with a reflected step spectrum profile. This characteristic minimizes the spectrum allocated to each sensor in a series multiplexing topology. By measuring the changes in the peak wavelength and spectral width of this signature, resolutions of ±0.65 °C/√Hz and ±2.55 μɛ/√Hz were achieved for temperature and strain measurements, respectively.