A wide-band optical frequency comb is provided to estimate an optical phase shift induced in a dispersive material. In contrast to the conventional techniques that rely on a single tunable laser for extracting the dispersion parameter at different frequencies, the wide-band optical frequency comb uses multiple comb lines for simultaneously evaluating the dispersion induced phase shifts in different frequencies. Since the frequency response of the dispersive material is a phase function, a phase associated with each comb line passed through the material represents a discrete measure of the material frequency response.