Distributed sensing network using a chirped ultra-weak fiber Bragg grating array

A distributed sensing network using a chirped ultra-weak fiber Bragg grating array is proposed and experimentally demonstrated. This network is based on time-division multiplexing (TDM) technique. We use a path-match interferometry to obtain interference signal, then amplitude, phase, frequency and location information can be demodulated from interference signal by employing the passive 3 × 3 coupler demodulation technique. Experiment was demonstrated on detecting vibration signals on the tracks, the vibration signals generated by a piezoelectric transducer (PZT), and underwater acoustic waves driven by a signal generator. The experimental results show that this system can well demodulate vibration signals generated by PZT and acoustic signals under the water with a relatively frequency response between 50Hz to 800Hz.