Ultrashort pulse

Measurement techniques

Several techniques are available to measure ultrashort optical pulses:

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• intensity autocorrelation: gives the pulse width when a particular pulse shape is assumed;
• spectral interferometry (SI): a linear technique that can be used when a pre-characterized reference pulse is available. Gives the intensity and phase. A self-referenced, nonlinear version is also used with a reference pulse with a frequency shear. The algorithm that extracts the intensity and phase from the SI signal is direct.
• frequency-resolved optical gating (FROG): a nonlinear technique that gives the intensity and phase. It's just a spectrally-resolved autocorrelation. The algorithm that extracts the intensity and phase from the FROG trace is iterative