Optical Fiber Acoustic Sensor Enhanced by Negative Poisson's Ratio Metamaterial Sleeve

Sensitivity enhancement of extrinsic Fabry–Perot interferometric (EFPI) acoustic sensor is basically limited by an over-reliance on diaphragm material and structure, as typical designs, the supporting sleeve is explicitly treated as a rigid and mechanically inactive component, thereby neglecting its potential structural deformation contribution. To break this design paradigm and actively harness supporting sleeve deformation for amplified acoustic response, this paper proposes and experimentally demonstrates a highly sensitive EFPI acoustic sensor integrated with a negative Poisson's ratio (NPR) metamaterial sleeve. By combining the NPR structure's intrinsic mechanical compliance with the auxetic-driven uniform deformation, the sensor achieves an amplified cavity-length modulation without compromising robustness. Following the optimization of structural parameters via a Cauchy mutation particle swarm optimization (CM–PSO) algorithm and subsequent simulation-based characterization, the sensor is fabricated using 3D printing technology. Experimental results reveal that sensitivity is up to 207.334 mV/Pa at 11.98 kHz, with a signal-to-noise ratio of 78 dB, and the sensor presents a broad response bandwidth of 1.00 kHz – 25.00 kHz. The minimum detectable pressure reaches 7.69 μPa/Hz1/2at 11.98 kHz. These experimental results represent a substantial advancement over typical EFPI sensors. Given its superior sensitivity, simplified manufacturing process and wide bandwidth, this sensor holds significant potential for underwater acoustic communications, environmental monitoring and high-end industrial applications.