Group Delay Dispersion Measurement From a Spectral Interferogram Based on the Cubic Phase Function

A novel group delay dispersion (GDD) measurement from a spectral interferogram is presented. Based on the cubic phase function (CPF) of the interference term, the GDD can be directly read from the ridge of CPF without phase retrieval and numerical differentiation operation. The proposed method is applied to measure the GDD and chromatic dispersion difference (CDD) of a polarization-maintaining fiber. The experimental results are unambiguous and insensitive to the filter choice of interference term calculation. GDD measurement can reach a resolution of 1 fs², with a processing time of 25 s for 1001 wavelength points, and CDD measuring deviation is less than 0.5 fs/(km·nm) around the center wavelength. The method is expected to be suitable for processing all spectral interferograms with polynomial phases.