Research on Real-time Correction Technique of FBG Demodulation

In the FBG demodulation system based on tunable fiber Fabry-Perot(F-P) interferometer,the system error increases due to the relationship of the driving voltage and the scanning wave peak,so the correction technology is studied in this paper.Firstly,a parallel real-time correction system is designed based on scheme comparison and analysis.This system corrects nonlinear problems of PZT and structural errors of the tunable FP interferometer using multiple reference points.Secondly,the relation between PZT driving voltage and the peak of tunable FP interferometer is analyzed by experiments.Then a fast segmentation algorithm is designed.Finally,a signal processing unit using field programmable gate array(FPGA) as the core is designed.This unit can guarantee real time work by integrating the demodulation system control,filter calculation and data compression circuits into one FPGA chip.Experimental results show that the mean square error of the system is 2.2 pm and the maximum error is 6 pm.Also the system measurement accuracy is improved,which solves the problem caused by accuracy limitation of the tunable FP interferometer.