A heat-resistance and high-sensitivity acoustic pressure sensor based on aluminum-polyimide diaphragm

A fiber-optic acoustic pressure sensor based on aluminum-polyimide diaphragm is proposed in this paper. The sensing diaphragm exhibits excellent properties including heat resistance and long-term stability (4 months). Together with hybrid configuration of Mach-Zehnder and Sagnac interferometer with triple detection passive demodulation algorithm, the sensor can measure the absolute amplitude of acoustic pressure. The sensor has a high sensitivity of 110 nm/Pa with the acoustic pressure amplitude of 2.05 mPa-7.15 Pa and gives a minimum detectable pressure of 37.7 μPa/Hz1/2 at 4 kHz. The sensor also demonstrates a flat frequency response in the range of 600 Hz-6 kHz and is expected to be used for weak acoustic pressure sensing and photo-acoustic spectroscopy.