MEMS-Based High-Sensitivity Fabry–Perot Acoustic Sensor With a 45° Angled Fiber

A high-sensitivity cross-axial extrinsic fiber Fabry–Perot interferometric acoustic sensor with a 45° angled fiber is proposed. The thickness of pressure-sensing silver diaphragm is 95 nm. The diameter is 1.6 mm yet the flatness of the diaphragm is
$<30~\mu \text{m}$
. The measured dynamic sensitivity of the diaphragm is 67.01 nm/Pa. The sensor exhibits a flat frequency response in the range of 1–6 kHz and a dynamic range of 66.43 dB. The minimal detectable pressure is
$\sim 107~\mu $
Pa/Hz
$^{1/2^{^{^{}}}}$
at 3 kHz. The fabricated sensor is expected to be useful for highly sensitive acoustic measurement.