Vibration sensors are of crucial importance in structural health monitoring and fault diagnosis within industries like aerospace, transportation, and precision machinery. Through the accurate capture and analysis of vibration signals, potential faults can be effectively predicted and prevented, thus enhancing the reliability and safety of the system. Compared with traditional electronic vibration sensors, fiber-optic vibration sensors have been widely studied due to advantages of high sensitivity, electromagnetic interference resistance, and remote detection capability. They are mainly classified into two categories: fiber Bragg grating (FBG) types and interferometric types. Among them, FBG vibration sensors are restricted by axial sensitivity characteristics of optical fibers and the temperature-strain cross-coupling effect, and their ability to decouple multiple physical fields and conduct broadband measurement is limited. Vibration sensors based on Fabry-Perot interferometry (FPI) provide a highly promising alternative solution to the above problems, but further breakthroughs are still needed in miniaturization, high dynamic response, broadband detection, and high-resolution signal demodulation. We endeavor to create an innovative micro-electro-mechanical system (MEMS) based FPI vibration sensor with the intention of tackling a diverse range of challenges. The sensor is equipped with a circular curved beam diaphragm, optimized spectral phase demodulation algorithm, and field-programmable gate array (FPGA) acceleration processing technology to achieve high dynamic response, ultra-wide measurement range, and strong environmental adaptability.

We integrate finite element simulation, MEMS micro-nano processing, ceramic packaging technology, and advanced signal processing techniques through a multidisciplinary collaborative approach to construct a high-performance fiber optic vibration sensing system. Firstly, by designing a circular composite elastic membrane structure with three pairs of bent beams arranged with 120° circumferential symmetry, a precision coupled spring mass system is constructed. Finite element analysis software is used to determine the resonance frequency of the membrane under different beam widths, beam thicknesses, mass block thicknesses, and mass block radius sizes. An optimized scheme with a resonance frequency of 6134 Hz is determined, and its wide working bandwidth within 1/3 of the resonance frequency meets mainstream industrial vibration detection requirements. Then, the 8 mm×8 mm micro-sensor is packaged using alumina ceramic encapsulation technology, combined with a demodulation algorithm based on spectral Fourier transform peak finding and phase estimation to effectively suppress phase jump errors and improve dynamic response characteristics. Finally, a demodulation system consisting of broadband light source, spectral module, and FPGA is built, and hardware acceleration of spectral preprocessing, fast Fourier transform, and spectral phase demodulation algorithm are achieved through a pipeline architecture. Finally, the cavity length data and interferometric spectra are synchronously transmitted to the upper computer via the universal serial bus (USB) interface. During the experimental verification phase, a reference level piezoelectric accelerometer with a sensitivity of 100.14 mV/g and a frequency response covering 1?10000 Hz is used for synchronous calibration. Accurate data calibration is achieved by placing the sensor on an electromagnetic vibration table, and the measured system’s dynamic response characteristics are significantly better than traditional demodulation schemes.

After the completion of the vibration testing system, the demodulation rate of 20 kHz is first verified using a testing device based on piezoelectric transducer (PZT), and the stability of the sensor is verified through a 60-s background noise test. Under soundproof conditions, the fluctuation of the Fabry-Perot (FP) cavity length is measured to be stable within ±0.1 nm, fully demonstrating the excellent stability and demodulation resolution of the designed sensor. Secondly, through frequency response testing, the operating bandwidth of the sensor is found to cover 0?1400 Hz when it is under 1g excitation. The resonance frequency measured by the impact test is 5356 Hz, which is basically consistent with the simulated resonance frequency. Subsequently, the vibration acceleration response of the fiber-optic vibration sensor is tested with a vibration table. These acceleration sensitivities measured at 200, 400, and 600 Hz are 18.135 nm/g, 18.347 nm/g, and 18.577 nm/g, respectively, with linear fitting coefficients of 0.999. This indicates that the vibration sensor exhibits extremely high acceleration linearity within its operating range. To verify the consistency of the vibration sensor, three repeated tests are conducted, and the linearity is measured to be 0.094%. The anti-interference test shows that the ratio of cross sensitivity to axial sensitivity under 600 Hz excitation is less than 7.649%, and the anti-interference ability in multi-dimensional vibration environment is verified. Finally, to evaluate the maximum measurement range of the sensor, limited by equipment conditions, a free fall impact test is used to successfully capture a 200g half sine waveform, and the dynamic range of ±182g is verified through sensitivity conversion.

In this paper, a circular curved beam structure elastic membrane is developed based on MEMS technology, and a fiber-optic FP vibration sensor is integrated with a ceramic bracket. Furthermore, a spectral-phase demodulation algorithm is constructed based on FPGA hardware, achieving high dynamic response detection capability at 20 kHz. Experimental tests have shown that the resonant frequency of the developed sensor is 5356 Hz, and its axial sensitivity is 18.577 nm/g @ 600 Hz. The repeatability is measured at 600 Hz to be less than 0.094%, the resolution can be reached to 0.01g, and the maximum measurement range has been extended to ±182g. Owing to its characteristics of wideband response, large measurement range, high resolution, and fast dynamic response, the proposed sensor has broad prospects in aerospace application.