A Wide-Frequency Optical Fiber-Tip Vibration Sensor Based on Two-Photon 3-D-Printed Annular Resonant Cavity

Accurate in-situ acquisition of high-frequency vibration signals remains a critical technical challenge. Conventional vibration sensors suffer from limited bandwidth and insufficient dynamic response, making them inadequate for effectively capturing high-frequency signals. To address these limitations, this study proposes a novel fiber-optic vibration sensor based on the Fabry-Pérot (F-P) interference principle. The sensor adopts an integrated design in which a resonant cavity, sensing diaphragm, and hollow cavity are directly fabricated onto the tip of a single-mode optical fiber using two-photon 3D printing technology. Finite element analysis (FEA) was employed to optimize the structural parameters. Experimental results demonstrate that the sensor effectively captures both continuous high-frequency vibrations and transient impact signals. Specifically, the sensor exhibits a broad frequency response ranging from 115 kHz to 305 kHz, and maintains an average sensitivity of 25 mV/g within the range of 0.5 to 10 kHz. The signal-to-noise ratios (SNR) of the sensor are as high as 45.5 dB@115kHz and 58.8 dB@305kHz, respectively. This performance demonstrates that proposed sensor is among the most advanced in the family of fiber-optic vibration sensor, with significant potential for applications such as structure health monitoring, ultrasonic detection, and mechanical fault diagnosis.