Abstract
A universal method is proposed for fast tracking the peak wavelength of a fiber Bragg grating (FBG) reflection spectrum, which is the essential procedure of most FBG interrogators. Assuming the FBG reflection spectrum is sampled uniformly, we decompose the Moore–Penrose of the coefficient matrix into a formula that only contains a division and a dozen additions and multiplications; thereby, the cost of computation can be greatly reduced. Based on the analysis of the characteristics of the error introduced by the spectrum’s nonlinearity, we found and defined an error associated with the distance between the sampled peak and actual peak, and the compensating method for the error is also given. After compensation, the proposed method can speed up the tracking process 10 times or more without sacrificing the accuracy. An economical FBG interrogator with a commercial field programmable gate array (FPGA) and a microspectrometer was built up to verify the method, which was able to achieve a measurement frequency of 17 kHz.
© 2020 Optical Society of America
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