Optical Fiber Fabry–Perot Acoustic Sensors Based on Corrugated Silver Diaphragms

In this article, we fabricated and tested a series of extrinsic fiber Fabry-Perot interferometric acoustic sensors based on the corrugated silver diaphragms. These diaphragms were fabricated through a simple and low-cost method. The corrugations were first etched on the silicon surface permanently and then transferred to the silver diaphragm with the help of photoresist as the sacrificial layer. The sensors with different corrugation depths were fabricated. The experimental results showed the same trend with the theoretical results on the mechanical sensitivities of the fabricated corrugated diaphragms, which first increased and then decreased with the increase in the corruption's depth. Other characteristics of the fabricated optical acoustic sensors based on the corrugated silver diaphragms were also tested in detail. The proposed fabrication method of the corrugated diaphragm showed the advantages of simplicity and low cost, and the acoustic sensors showed high sensitivity, which was suitable for weak acoustic's sensing.