提出一种采用π/2正交相位板的抗温度干扰光纤声传感器。采用微加工技术研制了一种具有π/2正交相位的波前相位板。经自聚焦光纤准直的光束通过π/2正交相位板可以形成波干涉,由此形成一个微型正交干涉型声波传感器。实验结果表明,所提传感器的声波频率为0.1~10 kHz时,声波响应灵敏度可达168 mV·Pa ^-1。在频率为5 kHz时,光纤声传感器的最小可探测声压可达68 μPa·Hz ^-1/2。因为π/2正交相位板具有固定的正交相位,所提传感器具有抗温度干扰能力。当环境温度为20~140 ℃时,传感器的电压标准变化量只有2.4%。所提传感器在远程气体泄漏探测、光声光谱探测、声源定位等方面具有广阔的应用前景。

In this paper, a temperature insensitive fiber acoustic sensor with a π/2 quadrature phase plate is proposed. A wavefront phase plate with π/2 quadrature phase is fabricated by micromachining technology. Beam collimation through a self-focusing fiber can create wave interference through the π/2 quadrature phase plate, thus forming a miniature quadrature interference acoustic sensor. The experimental results show that when an acoustic frequency of 0.1-10 kHz for the proposed sensor, the acoustic response sensitivity reaches 168 mV·Pa ^-1 and the minimum detectable acoustic pressure can be 68 μPa·Hz ^-1/2 at a frequency of 5 kHz. Notably, the proposed sensor is almost insensitive to temperature fluctuation because of the fixed quadrature phase of the π/2 quadrature phase plate. The voltage standard variation of the proposed sensor is only 2.4% in a wide range from 20 ℃ to 140 ℃. The proposed sensor is very promising in several applications in remote gas leak exploration, photoacoustic spectroscopy detection, and sound location.