Linear spatial temperature distribution fibre Bragg grating sensor

A study is presented of the application of commercially available FBGs (fibre Bragg gratings) to measure temperature gradients. The optical measurement system is based on an electronically tuned solid-state laser, S-TLD. FBG sensor calibration is carried out using a dual Peltier water-cooled system, with which linear temperature gradients are applied to the FBG, resulting in chirping along the grating. Spectral parameters are extracted from reflection intensity spectra using LabView software. A 'look-up table' approach is then used as a means of solving the inverse problem. Quantified worst-case errors associated with each estimated temperature value are presented, and in this way the accuracy of the temperature measurements are discussed. Based on our experimental results a novel proposal to use pre-chirped FBGs to optimize temperature gradient sensing is made.