High-Performance Compact Fiber Optic Interferometric Accelerometer Based on a Novel Push-Pull Structure

We demonstrate a compact fiber optic accelerometer (FOA) utilizing a push-pull spring-mass structure with a size of 25 mm × 25 mm × 25 mm, showcasing the excellent performance of strong sensitivity, minimal self-noise, and wide dynamic range. The presented sensing probe is a Michelson interferometer (MI) that employs the 3 × 3 coupler demodulation method to extract the information of vibration. Both arms of the MI are fiber coils wrapped around a movable push-pull folding spring structure, serving as the sensing arm for detection, which results in twice the sensitivity compared to a single-sensing arm accelerometer. The theoretical design and finite element analysis are validated experimentally, confirming that the proposed FOA demonstrates a mean sensitivity of 48.73 dB re rad/g over the frequency band of 5 Hz-1 kHz, closely matching the simulated results. It also achieves a large dynamic of 161.12 dB at 50 Hz. Noise evaluation experiment results reveal a low average noise level of 15.85 ng/Hz1/2 of the proposed sensor, indicating that it is one of the fiber optic interferometric accelerometers with the lowest noise reported to date.