摘要
A microscale fiber-optic sensor based on the Fabry-Pérot interferometric principle is proposed and experimentally demonstrated. The device comprises a single-mode optical fiber, a hollow-core capillary, and an ultrathin metallic diaphragm, forming a compact sensor structure with advantages of low-fabrication cost, simple manufacturing, and ultrasmall dimensions. The dual-parameter sensing strategy exploits time-scale separation and complementary demodulation domains, using intensity-based demodulation at a fixed quadrature point to capture fast acoustic-induced phase perturbations, while the temperature sensing is achieved by tracking the slow spectral drift of the interference fringes caused by the thermal expansion and thermooptic effects. Comprehensive multiphysics experiments were conducted to evaluate both acoustic and thermal sensing capabilities, with emphasis on the effect of diaphragm thickness on the overall performance. The acoustic characterization revealed a wide frequency response from 10 Hz to 20 kHz, a maximum signal-to-noise ratio (SNR) of 46.1 dB, a minimum total harmonic distortion (THD) of 0.051%, and a minimum detectable pressure (MDP) of 12.9 μPa/√Hz at 1 kHz. Thermal measurements confirmed reliable operation over 50 ◦C-300 ◦C, achieving a sensitivity of 13.3 pm/◦C with excellent linearity (R2 > 0.99). These results demonstrate that the proposed Fabry-Pérot fiber-optic sensor provides high-performance and cost-effective solutions for applications in acoustic detection, temperature monitoring, and wearable sensing technologies.