An optimized distributed fiber Bragg grating sensing system based on optical frequency domain reflectometry

In this paper, the waveforms in time domain and frequency domain of two kinds of optical frequency domain reflectometry (OFDR) sensing systems are compared, which use common fiber Bragg grating (FBG) and chirped grating, respectively. The results show that chirped fiber grating with about 3 nm of full width at half maximum (FWHM) is helpful to reduce frequency noise evidently and makes the characteristic frequency distinct. OFDR distributed sensing system with chirped grating also offers longer available time, which makes it convenient to measure slow time-varying signal. Such OFDR distributed sensing system is supposed to be more suitable to be applied in bridge health monitoring, and it will improve the accuracy and reliability of the measurement.