Common-mode noise self-suppressed 3-component fiber optic accelerometer based on low-reflectivity Bragg gratings.

Abstract

Common-mode noises (CMNs) are frequent in the fiber optic accelerometer, and their suppression is extremely important, particularly in the ultra-weak signal detection application, e.g., micro-seismic monitoring. This Letter proposes a 3-component (3C) low-reflectivity fiber Bragg gratings accelerometer for CMN self-suppression. When compared with the traditional CMN suppression method, the proposed 3C accelerometer is able to improve the CMN suppression effect by an average value larger than 4.5 dB in three axes, as well as double the effective signal amplitude due to the push-pull structure, which brings an enhanced signal-to-noise ratio. Besides, the proposed 3C accelerometer does not need an additional reference interferometer to achieve such a CMN suppression effect; hence, it largely reduces the volume and cost of the sensing system, which shows huge advantages, particularly in the large-scale quasi-distributed array. The proposed 3C accelerometer provides a promising candidate for the weak vector vibration detection.