A Corrugated Diaphragm-Based Fabry-Perot Ultrasonic Sensor by Two-Photon 3D Printing

A polymer corrugated diaphragm-based fiber-optic Fabry-Perot (FP) interferometer is proposed as an ultrasonic sensor and directly fabricated on an optical fiber tip by direct laser writing via two-photon polymerization. The structure of the corrugated diaphragm is optimized, and the mechanical properties are investigated numerically. The experimental results show that the proposed device has a resonant frequency of ~150 kHz and an enhanced mechanical sensitivity of 367.73nm/kPa@100 kHz, and a low noise equivalent level of 1.92 mPa/Hz1/2@100 kHz. The sensitivity is much higher that of FP devices with uniform diaphragm, demonstrating that the designed sensor is capable of detecting weak ultrasonic waves.