Study on the Sensitization Effect of Flywheel-Like Diaphragm on Fiber-Optic Fabry-Perot Acoustic Sensor

Abstract

A flywheel-like sensitive diaphragm, which breaks the sensitivity limitations imposed by the increased thickness and the decreased radius in edge-clamped circular structure, has been proposed and analyzed in fiber Fabry-Perot (FP) acoustic sensor. A new model is built around the effect of diaphragm's structure parameters on sensitivity of a fiber FP acoustic sensor with common ductile material. The proposed sensor based on flywheel-like stainless diaphragm in 5mm diameter and 0.035mm thickness has been fabricated and its acoustic performances were tested. The test results show that our acoustic sensor can realize acoustic measurement from 0.1 kHz to 19 kHz. The sensor exhibits an acoustic pressure sensitivity of 1.525nm/Pa at the frequency of 4.5 kHz. The noise-limited minimum detectable pressure (MDP) level of $\sim 13.06~\mu Pa/\sqrt {Hz} \text{@} 4.5\textrm {kHz}$ and the acoustic pressure signal-to-noise ratio (SNR) of 70.42 dB@4.5kHz are achieved, respectively. And the mean SNR of cavity length variation of 62.43dB can be acquired over the entire frequency range. Comparing with the edge-clamped circular structure, the flywheel-like structure endows the common ductile sheet material the ability to response to acoustic pressure. Cost-effective and compact size give the proposed acoustic sensor a competitive edge, something of crucial importance to commercial applications.