title: Spectrum interrogation of fiber acoustic sensor based on self-fitting and differential method.
abstract: In this article, we propose an interrogation method of fiber acoustic sensor to recover the time-domain signal from the sensor spectrum. The optical spectrum of the sensor will show a ripple waveform when responding to acoustic signal due to the scanning process in a certain wavelength range. The reason behind this phenomenon is the dynamic variation of the sensor spectrum while the intensity of different wavelength is acquired at different time in a scanning period. The frequency components can be extracted from the ripple spectrum assisted by the wavelength scanning speed. The signal is able to be recovered by differential between the ripple spectrum and its self-fitted curve. The differential process can eliminate the interference caused by environmental perturbations such as temperature or refractive index (RI), etc. The proposed method is appropriate for fiber acoustic sensors based on gratings or interferometers. A long period grating (LPG) is adopted as an acoustic sensor head to prove the feasibility of the interrogation method in experiment. The ability to compensate the environmental fluctuations is also demonstrated.
authors.forename: Xin
authors.initials: X
authors.lastname: Fu
authors.forename: Ping
authors.initials: P
authors.lastname: Lu
authors.forename: Wenjun
authors.initials: W
authors.lastname: Ni
authors.forename: Hao
authors.initials: H
authors.lastname: Liao
authors.forename: Shun
authors.initials: S
authors.lastname: Wang
authors.forename: Deming
authors.initials: D
authors.lastname: Liu
authors.forename: Jiangshan
authors.initials: J
authors.lastname: Zhang