Fiber-optic Fabry-Perot interferometer based high sensitive cantilever microphone

We demonstrate a high sensitive cantilever microphone based on fiber-optic Fabry-Perot interferometer. A stainless steel cantilever is manufactured by laser micro-machining technique. The size of the cantilever is 2 mm × 1 mm, and the thickness is 10 μm. The air gap between the fiber endface and the cantilever forms the Fabry-Perot cavity. Acoustic sensing test demonstrates high sensitivities in the frequency range from 100 Hz to 3 kHz. The pressure sensitivity and the noise-limited minimum detectable acoustic pressure level are measured to be 364 nm/Pa and 8.5 μPa/Hz1/2 at the frequency of 1 kHz, respectively. The Fabry-Perot interferometer based cantilever microphone shows advantages of high sensitivity, small size, easy to install and immune to electromagnetic interference.