The light source of fiber grating sensing system provides energy for the system. The stable and continuous light source is crucial for the application of the whole demodulation system. When the Modulated Grating Y-branch (MG-Y) laser is used as the light source of the fiber grating demodulation system, it is necessary to solve the problem that it is difficult for the MG-Y laser to quickly obtain the stable and continuous tuning within the required specific wavelength range.

In order to obtain the stable and continuous wavelengths quickly for MG-Y lasers, the K-Means (KMeans) clustering model is proposed and applied to obtain high-quality current-wavelength Look Up Table (LUT) for MG-Y lasers.

By combining the tuning characteristics of the MG-Y laser with the KMeans clustering model method, the centroid of the optimal tuning parameter curve in the phase tuning region of the LUT can be quickly obtained with time of about 18.26 s. Then, according to the tuning characteristics of the left, right and phase of the MG-Y laser itself, the fine tuning of the MG-Y laser wavelength can be achieved by uniform interpolation method. The LUT with the full tuning range is obtained from the KMeans clustering model, and the target LUT is selected at a certain interval. According to the output wavelength issued by the laser according to the target LUT, the mean value of the measured wavelength and the absolute value of the error of the target wavelength is 0.18 pm. The standard deviation of the absolute value of the error is 0.52 pm. Therefore, the MG-Y laser can be used as a stable light source for the fiber grating sensing system.

It is verified by experiments that the traditional manual search for each phase tuning region needs at least 30 min to find the centroid point. The same operation can be completed by KMeans clustering model method, which can greatly shorten the time to find the centroid point. Based on this method, the stable wavelength of quasi-continuous tuning can be achieved by controlling the MG-Y laser.