Ultrashort pulse measurements by interferometric spectrogram.

We experimentally demonstrate that an interferometric spectrogram (i.e., fringe- and frequency-resolved autocorrelation trace) with high signal-to-noise ratio can be processed by three different procedures to accurately retrieve the spectral phase profile. We also show that the data redundancy built in the interferometric spectrogram permits simultaneous retrieval of multiple spectral phase solutions, and their weighted average may give a highly robust result against the measurement noise.