Abstract: In order to measure the center wavelength of Fiber Bragg Grating (FBG) accurately, a high precision test system for wavelength of FBG is designed, it mainly consists of a tunable laser and a optical power meter, the measurement is achieved by using the method of wavelength sweeping. The output of tunable laser has advantage of high wavelength accuracy and signal to noise ratio, through wavelength sweeping at full scale range of optical power meter, the high precision and wide dynamic range reflected spectrum of FBG is obtained, four polynomial fitting is then applied to calculate the center wavelength. The measurement results showed that in the wavelength range of (1 520~1 590)nm, the measurement repeatability is better than 0.5pm, the uncertainty of measurement is 2pm (k=2), it can fulfill the measuring requirement of FBG which wildly used in sensing field.

Key words: Fiber Bragg Grating, Center wavelength, Wavelength sweeping