Diaphragm based long cavity Fabry-Perot fiber acoustic sensor using phase generated carrier

摘要

A diaphragm based long cavity Fabry-Perot interferometric fiber acoustic sensor is proposed. The Fabry-Perot cavity is formed by a flat fiber facet and an ultra-thin silver diaphragm with a 6-meter long fiber inserted in the cavity. A narrow-linewidth ring-cavity erbium-doped fiber laser is applied to demodulate the sensing signal in the phase generated carrier algorithm. Experimental results have demonstrated that the phase sensitivity is about - 140 dB re 1 rad/mu Pa at 2 kHz. The noise equivalent acoustic signal level is 60.6 mu Pa/Hz(1/2) and the dynamic range is 65.1 dB-SPL at 2 kHz. The sensor is suitable for sensing of weak acoustic signals. (C) 2016 Elsevier B.V. All rights reserved.