In order to effectively enhance the sensitivity and response range of optical fiber Fabry–Pérot (FP) ultrasonic sensors, this article proposes an implementation method of an optical fiber FP ultrasonic sensor with a controllable cavity length and variable diaphragm. On the basis of optimizing the viscosity coefficient of the polydimethylsiloxane (PDMS) material, a PDMS diaphragm with the thickness ranging from 20 to 60 µm is fabricated on the end face of a Φ200/128 µm hollow glass tube using a multiple transfer method. Then, a piece of Φ125 µm single-mode optical fiber is threaded into the hollow glass tube from the other end and encapsulated to form an optical fiber FP ultrasonic sensor based on a PDMS diaphragm. The intensity of the corresponding ultrasound signal and its spectral characteristics can be inverse-analyzed by detecting the FP interference spectra formed on the fiber end and the PDMS diaphragm surface under the action of dynamic ultrasound signals. The experimental results show that the highest ultrasonic detection frequency response of the proposed PDMS diaphragm optical fiber FP ultrasonic sensor can reach 430 kHz and the signal-to-noise ratio can reach up to 70 dB. The above-mentioned results indicate that the optical fiber FP ultrasonic sensor with a PDMS diaphragm proposed in this article has obvious advantages in terms of sensitivity and response range.

中文翻译：

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基于聚二甲基硅氧烷膜片的光纤超声波传感器，具有高灵敏度和宽光谱响应范围

为了有效提高光纤法布里-珀罗（FP）超声波传感器的灵敏度和响应范围，本文提出了一种腔长可控、膜片可变的光纤FP超声波传感器的实现方法。于优化聚二甲基硅氧烷（PDMS）材料的粘度系数的基础上，一个PDMS隔膜具有范围从20到60的厚度μ m的上的Φ200/ 128的端面制成μ中号使用多转印法中空玻璃管. 然后，一块 Φ125 µm单模光纤从另一端穿入空心玻璃管中并封装，形成基于PDMS膜片的光纤FP超声波传感器。通过检测在动态超声信号作用下在光纤端部和PDMS膜片表面形成的FP干涉谱，可以反分析出相应超声信号的强度及其光谱特性。实验结果表明，所提出的PDMS膜片光纤FP超声波传感器的最高超声波检测频率响应可达430 kHz，信噪比可达70 dB。上述结果表明，本文提出的带有PDMS膜片的光纤FP超声波传感器在灵敏度和响应范围方面具有明显的优势。