Square of the degree of coherence and dispersion-induced pulse broadening in a fiber-optic transmission

We describe a method for measuring optical pulse broadening with continuous wave beam emitted from a low-coherence source. A two-beam interferometer composed of nondispersive and dispersive arms makes it possible to obtain the dispersion-induced pulse broadening. Experiments are carried out using a standard single-mode fiber and a two-mode fiber in the 1560 nm-wavelength region. As a result, the square of the degree of coherence, |gamma|(2), well reflects the dispersion-induced pulse broadening for an unchirped Gaussian pulse. The theoretically derived relationship between these two physical phenomena well reflects the experimentally obtained results. Chromatic dispersion values obtained by the method are in good agreement with those obtained by the alternative method. The salient feature of the present method is clearly shown.