Fiber Bragg grating wavelength demodulation system based ondynamic scanning of distributed feedback laser

Through the study of the demodulation algorithm including the searching peak algorithm and fitting algorithm on the collected data (the domain signals of the Fabry-Perot (F-P) etalon transmission spectrum and fiber Bragg grating (FBG) sensors reflection spectrum) by the system, the FBG wavelength signal demodulation is achieved by way of combining C language programming with LabVIEW. As the collected data points consisted of the time-domain signals of F-P etalon transmission spectrum and FBG reflection spectrum by the system are discrete, and within 3 dB bandwidth the time-domain signal spectra of F-P etalon and FBG are in line with a Gaussian curve distribution, the Gaussian fitting is used for the collected data points to find the time point corresponding to the signal peak to improve system precision; Also, because of the certain nonlinearity of the distributed feedback laser (DFB) laser scanning wavelength with the scanning time, the binomial curve fitting is used to reduce the error caused by the nonlinearity. In addition, a standard FBG sensing channel is set for wavelength calibration. Experimental studies show that the system has a good stability, the wavelength measurement range is 1 550.012-1 554.812 nm, the resolution is 1 pm, the precision is 10 pm, verifying the feasibility of the system applying to the FBG wavelength signal detection.