Improving measurement accuracy of fiber Bragg grating sensor using digital matched filter

Abstract

Fiber Bragg grating (FBG) sensors are promising candidates for strain measurements in smart structures. The wavelength-encoded nature of the reflected signals from FBGs allows for absolute strain measurement and for multi-point operation based on wavelength division multiplexing (WDM). To measure strain variation with good accuracy, detection of the small shift in the Bragg wavelength is essential. In this paper, we report the use of a digital matched filter (DMF) for improving the wavelength detection accuracy. The DMF technique has been used extensively in image processing and pattern recognition for the detection of weak signals in a noisy environment. We apply it here for the detection of Bragg wavelength in FBG sensors when the SNR is low.