Highly sensitive and wide frequency response fiber-optic accelerometer array with switchable resonance frequency

To achieve distributed quantitative vibration monitoring, a mandrel-type fiber-optic accelerometer (FOA) array based on weak chirped fiber Bragg grating (wCFBG) is proposed, which has the advantages of high sensitivity and wide frequency response. The introduction of the diaphragm increases the stiffness of the FOA, and the resonant frequency can be switched by the flexible replacement of this assembly. The effect of the sensing fiber length on the FOA was experimentally investigated, and the designed FOA demonstrated a notable sensitivity of 39.47 dB @100 Hz. The FOA exhibits excellent flatness and a wide frequency response range, with a sensitivity fluctuation of 1 dB within 10–1400 Hz. The performance of the FOA was experimentally evaluated with different diaphragm thicknesses and numbers of arms. The FOA has a favorable lateral anti-interference ability, with a cross-axis sensitivity maintained below 2.87 % of the main axis. Additionally, a FOA array was constructed using the time-division multiplexing strategy based on wCFBG to achieve distributed vibration measurement. The proposed FOA array has the unique advantage of flexible resonant frequency switching, making it adaptable to vibration monitoring requirements in diverse scenarios.