Complete noise characterization of a Gigahertz optical pulse train by time-domain demodulation of its harmonics

By time-domain amplitude demodulation of the first three harmonics of a detected optical pulse train and by phase demodulation of two of them, we were able to determine power spectral densities of amplitude, pulse width and phase jitters, as well as the three cross-spectral densities of these three noises taken two by two. An outstanding result is that low-frequency noise of an actively mode-locked Er-doped fiber laser is free of pulse energy fluctuations.