Open AccessAcoustic emission sensor system using a chirped fiber-Bragg-grating Fabry–Perot interferometer and smart feedback control
Author(s) -
Qi Zhang,
Yupeng Zhu,
Xiangyu Luo,
Guigen Liu,
Ming Han
Publication year - 2017
Publication title -
optics letters/optics index
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.524
H-Index - 272
eISSN - 1071-2763
pISSN - 0146-9592
DOI - 10.1364/ol.42.000631
Subject(s) - fiber bragg grating , optics , fabry–pérot interferometer , interferometry , diffraction grating , fiber optic sensor , optical fiber , materials science , phosfos , grating , physics , polarization maintaining optical fiber , laser
We demonstrate a fiber-optic acoustic emission (AE) sensor system that is capable of performing AE detection, even when the sensor is experiencing large quasi-static strains. The sensor is a Fabry-Perot interferometer formed by cascaded chirped fiber-Bragg gratings (CFBGs). The reflection spectrum of the sensor features a number of narrow spectral notches equally spaced within the reflection bandwidth of the CFBG. A semiconductor laser whose wavelength can be fast tuned through current injection is used to lock the laser line to the center of a slope of a spectral notch. When the notch is knocked out of the tuning range of the laser, a neighboring notch moves into the range. Through a smart feedback control scheme, the laser is unlocked from the current spectral lock and relocked to the desired point of the new notch. The fast speed of the unlocking/relocking process (<1 ms) ensures that the AE signal is monitored without significant disruption.