Dispersion measurement of optical fibers based on a phase-locked unbalanced Mach–Zehnder interferometer

Abstract Accurate measurement of optical fiber dispersion is important for optical processing, such as optical communication, optical fiber-based quantum state generation, etc. In this paper, we propose a new method for measuring optical fiber dispersion that can accurately measure the dispersion of long optical fibers in a wide spectral range. By using a femtosecond laser and unbalanced Mach–Zehnder interferometer with a phase-locking system, the coherence length of the optical source and stability of dispersion measurement have been improved. Thus, we overcome the shortcomings of traditional dispersion measurement methods that are difficult to make compatible with long fibers and wide spectral ranges. Using this method, we measure the dispersion parameters of two pieces of dispersion shifted fiber (DSF) with lengths of 200 m and 300 m, respectively, in the wavelength range 1500–1600 nm. Measurement results show that the zero-dispersion wavelength (ZDW) and the zero-dispersion slope (ZDS) of the 200 m DSF are 1535.53 ± 0.05 nm and 0.034 ± 10 −4 ps nm –2 km −1 , respectively, while the ZDW and ZDS of the 300 m DSF are 1551.26 ± 0.06 nm and 0.040 ± 10 −5 ps nm –2 km −1 , respectively. We test the stability of the system by using the root-mean-square (RMS) fluctuations of six measurements of the dispersion parameter D ( λ ) for the two pieces of fiber; the RMS values are both less than 0.02 ps nm –1 km −1 . Our research is valuable for measurement of dispersion for long fibers within a wide spectral range, considering the effects of fiber uniformity.