Frequency division multiplexing of FBG sensors using an FMCW approach

We report on the use of a frequency-modulated continuous wave (FMCW) technique for multiplexing fiber Bragg grating (FBG) sensors. This technique is based on the modulation of light intensity for a broadband source by a linear swept-frequency RF carrier. Signals from the FBG sensors located at different positions in an array are separated in frequency-domain and demodulated using a tunable optical filter. The potential and limitation of the technique are discussed. A 3-sensor FMCW multiplexed FBG array of parallel topology and a 6-sensor hybrid FMCW/WDM system were experimentally demonstrated with -30 dB crosstalk between sensors and a 2(mu) (epsilon) resolution in terms of root-mean- square strain value.