Simultaneous temporal characterization of telecommunication optical pulses and modulators by use of spectrograms

We demonstrate a simple technique for simultaneous and complete characterization of the optical pulses and temporal modulators commonly used in telecommunication. The electric field of a pulse and the response of a modulator are obtained from the analysis of the two-dimensional spectrogram of the pulse gated by the modulator. The measurement sensitivity is greatly improved compared with the conventional nonlinear optical techniques. Trains of picosecond pulses as weak as ${10}^{-17} \mathrm{J}$ are accurately characterized with an electroabsorption modulator as the temporal gate. The time-resolved transmission and phase of the modulator are also presented.