Improving the signal-to-noise ratio in a fiber-optic Fabry–Pérot acoustic sensor

Abstract

A fiber-optic Fabry–Pérot acoustic sensor with a ~50 nm-thick multilayer graphene diaphragm is reported. In this paper, the results of the simulation and experimental investigation of the Fabry–Pérot acoustic sensor are primarily presented, and the main area of interest is studying the different algorithms for enhancement of the sensor sensitivity. The phase generated carrier (PGC) demodulation algorithm is presented, based on differential-cross-multiplying (DCM), the arctangent (ATAN) function and ATAN based on a coordinate rotation digital computer CORDIC algorithm. The simulation results reveal that the PGC demodulation method, based on the ATAN CORDIC algorithm, has a better result (signal-to-noise ratio) than the DCM and ATAN function without using the CORDIC algorithm. On this account, a PGC demodulation algorithm based on the ATAN method with a CORDIC algorithm is applied in the experimental investigation due to the simulation results and simpler digital implementation on a field programmable gate array. The acoustic sensor shows a high frequency response from 8–10 kHz and may be useful for highly sensitive acoustic sensing without temperature and pressure fluctuation. The results also show acoustic sensitivity in the order of −98 dB re rad µPa−1 at 1 kHz.