Yang Wen-Zhao, Jin Long, Liang Yi-Zhi, Ma Jun, Guan Bai-Ou
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou 510632, China.
Sensors (Basel). 2017 May 26;17(6):1219. doi: 10.3390/s17061219.
In this work, a beat-frequency encoded fiber laser hydrophone is developed for high-resolution acoustic detection by using an elastic corrugated diaphragm. The diaphragm is center-supported by the fiber. Incident acoustic waves deform the diaphragm and induce a concentrated lateral load on the laser cavity. The acoustically induced perturbation changes local optical phases and frequency-modulates the radio-frequency beat signal between two orthogonal lasing modes of the cavity. Theoretical analysis reveals that a higher corrugation-depth/thickness ratio or larger diaphragm area can provide higher transduction efficiency. The experimentally achieved average sensitivity in beat-frequency variation is 185.7 kHz/Pa over a bandwidth of 1 kHz. The detection capability can be enhanced by shortening the cavity length to enhance the signal-to-noise ratio. The minimum detectable acoustic pressure reaches 74 µPa/Hz at 1 kHz, which is comparable to the zeroth order sea noise.
在这项工作中，通过使用弹性波纹膜片开发了一种拍频编码光纤激光水听器，用于高分辨率声学检测。该膜片由光纤在中心支撑。入射声波使膜片变形，并在激光腔上产生集中的横向载荷。声学诱导的扰动改变局部光学相位，并对腔的两个正交激光模式之间的射频拍频信号进行频率调制。理论分析表明，更高的波纹深度/厚度比或更大的膜片面积可以提供更高的转换效率。在1kHz带宽内，实验实现的拍频变化平均灵敏度为185.7kHz/Pa。通过缩短腔长以提高信噪比，可以增强检测能力。在1kHz时，最小可检测声压达到74µPa/Hz，这与零阶海洋噪声相当。
