A fiber-optic Fabry-Perot acoustic sensor based on PDMS diaphragm

This paper proposes a low-cost detachable extrinsic Fabry-Perot (FP) acoustic pressure sensor (EFPAPS) based on a polydimethylsiloxane (PDMS) diaphragm. An FP microcavity with air as the medium is formed between the PDMS diaphragm and the fiber end face. The experimental results show that the fabricated sensor has a high optical contrast of approximately 7 dB, and its initial cavity length is $26.367 \mu m$. The minimum detectable sound pressure (MDP) at 100Hz and 420Hz are $14.826 \mu \mathrm{Pa} / \mathrm{Hz}^{1 / 2} \text{@} 100Hz$ and $26.9793 \mu \mathrm{Pa} / \mathrm{Hz}^{1 / 2} \text{@} 420Hz$ respectively. And The sound pressure sensitivities at these two frequencies are 2.5006 mV/Pa and 8.9524 mV/Pa respectively. The sensor’s high-precision measurement of medium and low-frequency sound waves and its simple preparation process make it expected to shine in the field of acoustic sensing.