Open AccessFiber Bragg grating dynamic strain sensor using an adaptive reflective semiconductor optical amplifier source
Author(s) -
Heming Wei,
Chuanyi Tao,
Yinian Zhu,
Sridhar Krishnaswamy
Publication year - 2016
Publication title -
applied optics
Language(s) - Uncategorized
Resource type - Journals
ISSN - 0003-6935
DOI - 10.1364/ao.55.002752
Subject(s) - fiber bragg grating , optics , materials science , phosfos , fiber optic sensor , optical amplifier , optical fiber , polarization maintaining optical fiber , optoelectronics , long period fiber grating , photonic crystal fiber , laser , physics
In this paper, a reflective semiconductor optical amplifier (RSOA) is configured to demodulate dynamic spectral shifts of a fiber Bragg grating (FBG) dynamic strain sensor. The FBG sensor and the RSOA source form an adaptive fiber cavity laser. As the reflective spectrum of the FBG sensor changes due to dynamic strains, the wavelength of the laser output shifts accordingly, which is subsequently converted into a corresponding phase shift and demodulated by an unbalanced Michelson interferometer. Due to the short transition time of the RSOA, the RSOA-FBG cavity can respond to dynamic strains at high frequencies extending to megahertz. A demodulator using a PID controller is used to compensate for low-frequency drifts induced by temperature and large quasi-static strains. As the sensitivity of the demodulator is a function of the optical path difference and the FBG spectral width, optimal parameters to obtain high sensitivity are presented. Multiplexing to demodulate multiple FBG sensors is also discussed.