High-sensitivity Fiber-optical Microphone Based on Dual-rib Structure

Fiber-optic microphones have emerged as an innovative solution in the field of acoustic sensing due to their compact size， excellent immunity to electromagnetic interference， and superior insulation performance. These attributes make them ideal for use in various challenging environments such as power systems， healthcare， petrochemical industries， and national defense. However， despite these advantages， traditional fiber-optic microphones still face challenges in terms of sensitivity， stability， and insulation， particularly in high-performance or demanding conditions. Some existing designs struggle with low sensitivity in detecting weak acoustic signals or may experience degradation in performance due to material instability and electromagnetic interference under extreme conditions. Additionally， ensuring stable insulation properties in high-temperature or harsh electromagnetic environments remains a challenge for many fiber-optic microphone designs. Therefore， this work proposes and fabricates a novel high-sensitivity fiber-optic microphone featuring a dual-rib diaphragm structure.The microphone unit consists primarily of a dual-rib diaphragm， a single-mode optical fiber， and a glass sleeve， which work in synergy to convert acoustic signals into optical signals for high-precision measurement. The diaphragm's design was optimized through finite element simulations to achieve the desired resonance characteristics and enhance its acoustic sensitivity. Specifically， the ribbed diaphragm structure was designed to increase its flexibility， thereby improving its response sensitivity to pressure changes. To fabricate the diaphragm， we employed a picosecond laser micro-nano machining system， which allowed us to achieve high precision and fine features in the diaphragm's ribbed structure. This fabrication process ensures that the diaphragm can withstand mechanical stresses during acoustic signal detection while maintaining high sensitivity.The fabricated fiber-optic microphone exhibits a high sensitivity of 1 418.9 mV/Pa and a signal-to-noise ratio of 60.47 dB at a resonance frequency of 15.58 kHz， demonstrating excellent performance in acoustic signal acquisition. The microphone's high sensitivity makes it suitable for detecting weak acoustic signals， even in environments with significant background noise. Moreover， the microphone displays a strong directional response， which is critical for applications that require precise localization of sound sources. These characteristics make it an excellent candidate for use in a variety of industrial and scientific applications， where accurate and reliable sound detection is required.The potential applications of this high-sensitivity fiber-optic microphone are vast. It is particularly suited for power sensing， where it can be used to detect weak acoustic signals from power equipment， monitor partial discharges， diagnose faults， and enable online monitoring of power lines. The microphone's immunity to electromagnetic interference and high sensitivity make it ideal for use in environments with high levels of electrical noise. In addition， the microphone's ability to detect low-level acoustic signals makes it a promising tool for applications in healthcare， such as monitoring bodily sounds， as well as in the petrochemical industry for detecting gas leaks and machinery failures. Beyond these initial applications， the fiber-optic microphone holds promise for many other emerging fields. For example， it could be integrated into advanced monitoring systems for industrial automation， where real-time acoustic feedback is used for predictive maintenance and early detection of mechanical failures. In the field of robotics， the microphone's small size and high sensitivity could be leveraged in autonomous systems for environmental sound detection and localization. Additionally， as wireless technology continues to advance， fiber-optic microphones could be used in conjunction with wireless communication systems for remote sensing applications， further extending their potential. Future research will focus on optimizing the diaphragm design to achieve a broader frequency response and enhancing the microphone's robustness in extreme environments. Additionally， efforts will be directed at improving the signal processing capabilities of the fiber-optic microphone to ensure high-performance operation in complex and diverse environments. This work lays a solid foundation for the development of high-sensitivity fiber-optic microphones， which will undoubtedly lead to their widespread application in high-performance acoustic sensing fields， offering substantial benefits for industrial， scientific， and healthcare applications.