Interferometric Fiber-Optic Vibration Sensor Array With Improved Response Bandwidth Based on Frequency Division Multiplexing Linear Frequency Modulation

A novel scheme for improving the vibration response bandwidth of interferometric fiber-optic sensor (IFOS) array is proposed and demonstrated in this article. The scheme is based on the frequency division multiplexing (FDM) linear frequency modulation, that is, one of the modulating signals is linear frequency modulated pulse train with different frequency ranges. Polarization diversity detection is adopted to enhance the sensitivity of vibration measurement, and matched filtering algorithm is used to demodulate the FDM chirped signals. A proof-of-concept experiment is implemented to validate the performance of single sensor. The vibration signals are detected with high signal-to-noise ratio (SNR) of over 30 dB ref rad²/Hz in experiments, and the frequency response bandwidth can achieve 500 kHz. The effectiveness of multiple sensors array is verified by simulation results. It is shown that the proposed method can improve the frequency response bandwidth by 5 times compared with the traditional time division multiplexing (TDM) sensing array under the same configuration, and the tradeoff between the number of sensors in the array and the vibration response bandwidth is solved.